BANCROFT  LIBRARY 

♦ 

THE  LIBRARY 
OF 
THE  UNIVERSITY 
OF  CALIFORNIA 


WALTER  WADSWORTH   BRADLEY 

1878-1950 

Walter  W.  Bradley  was  born  in  San  Jose  and 
received  the  degrees  of  B.S.  and  E.M.  from 
the  University  of  California.  From  1912  to 
1946  he  was  associated  with  the  California 
Division  of  Mines,  serving  as  State  Mineral- 
ogist for  the  last  eighteen  years  of  that  period. 
His  published  works  relate  to  mining,  proc- 
essing, and  geology.  This  book  is  from  his 
private  collection,  presented  to  the  Bancroft 
Library  by  Mrs.  Alice  Roberts  Bradley. 


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THE 


ORE    DEPOSITS 


OF    THE 


UNITED  STATES  AND  CANADA 


BY 

JAMES    FURMAN    KEMP,    A.B.,  E.M., 

PROFESSOR  OF  GEOLOGY  IN  THE  SCHOOL  OF  MINES,  COLUMBIA.  UNIVERSITY. 


FOLRTH  LDJTIOK 

ENTIRELY  REWRITTEN  AND  ENLARGED. 


NEW  YORK  AND  LONDON: 
THE  SCIENTIFIC  PUBLISHING  COMPANY, 

1901. 


FSV 

mi 


Copyright,  1893  and  1900, 

BY 

The  Scientific  Publishing  Company. 


PREFACE. 

The  following  pages  presuppose  for  their  apprehension 
some  acquaintance  with  geology  and  mineralogy.  The  mate- 
rials for  them  tiave  been  collected  and  arranged  in  connection 
with  lectures  on  economic  geology,  first  at  Cornell  University 
and  later  at  the  School  of  Mines,  Columbia  College,  To  the 
descriptions  of  others  the  author  has  endeavored  to  add,  as  far 
as  possible,  observations  made  by  himself  in  travel  during  the 
last  ten  years.  The  purpose  of  the  book  is  twofold,  and  this 
fact  has  been  conscientiously  kept  in  view.  It  is,  on  the  one 
hand,  intended  to  supply  a  condensed  account  of  the  metallifer- 
ous resources  of  the  country,,  which  will  be  readable  and  serv- 
iceable as  a  text- book  and  work  of  reference.  For  this  rea- 
son every  effort  has  been  put  forth  to  make  the  bibliography 
complete,  so  that,  in  cases  where  fuller  accounts  of  a  region 
are  desired,  the  original  sources  may  be  made  available  in  any 
good  library.  But,  on  the  other  hand,  it  has  also  been  the 
hope  and  ambition  of  the  author  to  treat  the  subject  in  such  a 
way  as  to  stimulate  investigation  and  study  of  these  interesting 
phenomena.  If,  by  giving  an  extended  view  over  the  field,  and 
by  making  clear  what  our  best  workers  have  done  in  late  years 
toward  explaining  the  puzzling  yet  vastly  important  questions 
of  origin  and  formation,  some  encouragement  may  be  afforded 
those  in  a  position  to  observe  and  ponder,  the  second  aim  will 
be  fulfilled.  In  carrying  out  this  purpose,  the  best  work  of 
recent  investigators  on  the  origin  and  changes  of  rocks,  espe- 
cially as  brought  out  by  microscopic  study,  has  been  kept  con- 
stantly in  mind,  and  likewise  in  the  artificial  production  of  the 
ore  and  gangue  minerals.  So  much  unsound  and  foolish  theo> 
rizing  has  been  uttered  and  believed  about  ores,  that  too  much 
care  cannot  be  exercised  in  basing  explanations  on  reasonable 
and  right  foundations. 


vi  PREFACE, 

Acknowledgments  are  due  to  many  friends  for  encourage- 
ment, suggestion,  and  criticism.  To  Prof.  Henry  S.  Williams, 
now  of  Yale,  but  late  of  Cornell,  whose  interest  made  the  book 
possible,  these  are  especially  to  be  made.  On  particular  regions 
much  advice  has  been  obtained  from  Dr.  W.  P.  Jenney,  for 
which  the  author  is  grateful.  In  the  same  way  Prof.  H.  A. 
Wheeler,  of  St.  Louis,  Prof.  R.  A.  F.  Penrose,  of  Chicago,  and 
several  other  friends  have  contributed.  Dr.  R.  W.  Raymond 
suggested  the  method  of  enumerating  the  paragraphs.  It  has 
the  advantages  of  being  elastic  and  of  showing  at  once  in  what 
part  of  the  book  any  paragraph  is  situated. 

The  geologists  of  the  United  States  Geological  Survey,  who 
have  been  engaged  in  the  study  of  our  great  mining  regions, 
especially  in  the  West,  have  laid  the  whole  scientific  world  un- 
der a  debt  of  gratitude,  and  in  this  country  have  probably  been 
the  most  potent  influences  toward  right  geological  conceptions 
regarding  ores.  Of  authors  abroad,  Von  Groddeck  has  been  a 
means  of  inspiration  to  all  readers  of  German  who  have  inter- 
ested themselves  in  this  branch  of  geology.  The  writer  cannot 
well  forbear  acknowledging  their  influence. 

Should  errors  be  noted  by  any  reader,  the  writer  will  be  very 
appreciative  of  the  kindness  if  his  attention  is  called  to  them. 

J.  F.  Kemp. 
Columbian  College,  in  the  City  of  New  York,  1892. 


PREFACE  TO  THE  SECOND  EDITION, 

In  the  second  edition  many  pages  have  been  rewritten  and  ex- 
panded. The  endeavor  has  been  also  made  to  introduce  into 
the  body  of  the  work  the  new  materials  that  have  become  avail- 
able in  the  last  year.  This  is  especially  true  of  iron  ores,  of  the 
geology  of  the  Sierras,  and  of  nickel  and  cobalt.  In  all  some 
fifty  pages  of  new  matter  have  been  added,  and  fifteen  cuts. 
Acknowledgments  are  herewith  made  to  Professors  W.  H. 
Pettee,  of  Ann  Arbor;  H.  S.  Munroe,  of  New  York;  and  C.  H. 
Smyth,  Jr.,  of  Hamilton  College;  and  to  Mr.  now  Prof.  H.  L, 
Smyth,  of  Cambridge,  and  Prof.  W.  C=  Knight,  of  Laramie, 
for  suggestions,  as  requested  in  the  preface  to  the  first  edition. 

1895,'  J.   F.   K. 


PREFACE  TO  THE  THIRD  EDITION, 

In  the  third  edition  the  title  has  been  expanded  so  as  to  in- 
clude Canada,  since  the  nature  of  the  contents  now  justifies  this 
change.  About  one  hundred  pages  of  new  matter  have  been 
added,  and  considerable  portions  of  the  former  text  have  been 
rewritten.  The  figures  have  been  doubled  in  number,  and 
many  maps  have  been  introduced.  The  writer's  thanks  are 
due  for  advice  and  assistance  to  Messrs.  W.  H.  Weed,  H.  Wo 
Turner  and  John  D.  Irving,  of  the  United  States  Geological 
Survey,  to  Mr.  H.  F.  Bain,  of  the  Iowa  Geological  Survey,  to 
Mr.  S.  S.  Fowler,  of  Nelson,  B,  C,  and  to  many  of  his  students, 
now  in  the  active  practice  of  the  profession  of  mining  engi- 
neering. J.  F.  K. 

December,  1899. 


ERRATA. 


Page  320,  line  28,  "  30  miles  east,"  not  "20  miles  west." 
Page  241,  fig.  78,  and  text  p.  243,  line  12  and  following. 
In  connection  with  the  diagram  and  its  intei'pvetation,  it 
should  be  stated  thatin.preparing  chart  proper  allowance 
has  not  been  made  for  the  varying  heights  of  the  loca- 
tions of  the  bore-holes  and  for  their  stratigi'aphical 
positions.  The  chart  shows  therefore  actual  depths  not 
stratigraphical  distribution. 


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TABLE  OF  CONTENTS. 


PAGS 

Preface , . ,      v 

List  of  Illustrations o .   xv 

List  of  Abbreviations xxi 

PART  I.— INTRODUCTOEY. 

CHAPTER  I.— General  Geological  Facts  and  Principles. 

The  two  standpoints  of  geology,  3,  4 ;  the  scheme  of  classificar 
tion,  4,  5 ;  classification  of  rocks,  6 ;  brief  topographical  survey  of 
the  United  States,  7,  8;  brief  geological  outline,  8-11;  forms  as- 
sumed by  rock  masses,  11,  12 1-12 

CHAPTER  n. — The  Formation  of  Cavities  in  Rocks. 

Tension  joints,  13,  14;  cleavage,  fissility,  and  compression 
joints,  14-16 ;  by  more  extensive  movements,  16-31 ;  faults,  21-25 ; 
zones  of  possible  fracture  in  the  earth's  crust,  25,  26  ;•  secondary 
modifications  of  cavities,  26-32. lS-32 

CHAPTER  in. — The  Minerals  Important  as  Ores;  the  Gangue 
Minerals,  and  the  Sources  whence  both  are  Derived. 

The  minerals,  32;  source  of  the  metals,  32-38 .82-38 

CHAPTER  IV.— On  the  Filling  of  Mineral  Veins. 

Resume,  39 ;  methods  of  filling,  39,  40 ;  lateral  secretion,  40 ; 
ascension  by  infiltration,  40-44;  replacement,  44-46 39-46 

CHAPTER  V. — On  Certain   Structural   Features  of  Mineral 
Veins. 

Banded  structure,  47-49;  clay  selvage,  49;  pinches,  swells, 
lateral  enrichments,  49,  50 ;  changes  in  character  of  vein  filling, 
50 ;  secondary  alteration  of  the  minerals  in  veins,  50-52 :  electrical 
activity,  52,  53 , .  .47-53 

CHAPTER  VI.— The  Classification  of  Ore  Deposits,  a  Review 
and  a  Scheme  Based  on  Origin. 

Statement  of  principles,  54,  55 ;  principal  schemes,  55 ;  scheme 
entirely  based  on  origin,  55-59 ;  remarks  on  the  above,  and  dis- 
cussion of  methods  of  formation,  59-73;  fahlbands,  73;  phrase- 
ology used,  73 ;  character  of  the  rocks  containing  the  deposits, 
73 ;  general  bibliography  of  ore  deposits,  74-79 ....  54-79 


X  TABLE  OF  CONTENTS. 

PART  II.— THE  ORE  DEPOSITS. 

PAGE 

CHAPTER  I. — The  Iron  Series  (in  Part). — Introductory  Remarks 
ON  Iron  Ores. — Limonite.^^iderite. 

General  literature,  83,  84;  table  of  analyses,  84;  general  re- 
marks on  composition  and  occurrence,  85-87 ;  Limonite,  Example 
1,  bog-ore,  87-92;  Examples,  brown  hematite  not  Siluro-Cambrian, 
92-100;  Example  2a,  Siluro-Cambrian  brown  hematites,  100-104; 
origin  of  same,  104,  105;  analyses  of  limonites.  106;  siderite  or 
spathic  ore,  introductory,  106;  Example  3,  clay  ironstone,  106, 
107;  Example  3a,  black-band,  107-110;  Example  4,  Burden  Mines, 
110,  111;  Example  5,  Roxbury,  Conn.,  112;  genetic  discussion  of 
siderite,  112,  113 83-113 

CHAPTER  II. — The  Iron  Series,  Continued— Hematites,  Red  and 
Specular. 

Introductory  remarks,  114 ;  Example  6,  Clinton  ore,  114-121 ; 
Greenbrier  Co.,  W.  Va.,  121;  Mansfield  ores,  Penn.,  121,  152;  Ex- 
ample 7,  Crawford  Co.,  Mo.,  122,  123;  Example  8,  Jefferson  Co., 
N.  Y.,  123-125;  Example  9,  Lake  Superior  hematites,  125;  intro- 
ductory, 125-129;  Marquette  district,  129-136;  Menominee  dis- 
trict, 136-139;  Penokee-Gogebic  district,  139-143;  Vermilion  Lake 
and  range,  144-150 ;  Mesabi,  150-154 ;  Example  10,  James  River, 
Va.,  154,  155;  Example  11,  Pilot  Knob,  Mo.,  155-157;  Example 
11a,  Iron  Mountain,  Mo.,  157,  158;  analyses  of  hematites,  159..  114-159 

Chapter  hi.— Magnetite  and  Pyrite. 

Example  12,  Magnetite  beds,  160;  Adirondack  region,  160- 
166;  New  York  and  New  Jersey  Highlands,  166-169;  South  Moun- 
tain, Penn.,  169;  Western  North  Carolina  and  Virginia,  169,  170; 
Colorado,  170,  171 ;  California,  171 ;  Example  13,  titaniferous  mag- 
netites, 171-175;  Example  14,  Cornwall,  Pa.,  175-180;  Example  14a, 
Iron  Co.,  Utah,  180;  Example  15,  magnetite  sands,  180, 181;  origin 
of  magnetite  deposits,  181-183 ;  analyses  of  magnetites,  183 ;  pyrite, 
184-186;  Example  16,  pyrite  beds,  184-186;  statistics,  186;  remarks 
on  Cuban  and  Mexican  iron  ores,  18S-188. ... 160-188 

CHAPTER  IV.— Copper. 

Table  of  analyses  of  copper  ores,  189 ;  Example  16,  continued, 
pyrite  beds,  189-194;  Spenceville,  Cal.,  195,  196;  Example  17, 
Butte,  Mont.,  197-203;  Gilpin  Co.,  Colo.,  203,  204;  Llano  Co., 
Texas,  204;  Example  18,  Keweenaw  Point,  Mich.,  204-209;  origin 
of  the  copper,  209-212;  Example  19,  St.  Genevieve,  Mo.,  313,  214; 
Example  20,  Arizona  Copper,  214,  215;  Morenci,  215,  216;  classi- 
fication of  ores  by  Henrich,  216,  217;  Bisbee,  217,  218;  Globe,  218, 
219;  Santa  Rita,  N.  M.,  219;  Black  Range,  220;  Copper  Basin, 
220;  Crismon-Mammoth,  Utah,  221,  222;  Wyo.,  Idaho,  Wash., 
222;  Example  21,  copper  ores  in  Triassic  or  Permian  sandstone, 
222-224;  Eastern  States,  323,  334;  Western  States,  334;  statistics 
of  copper,  225 189-225 


TABLE  OF  CONTENTS.  xi 


CHAPTER  V.—Lead  Alone. 

Introductory  and  analyses  of  lead  ores,  226 ;  Example  22,  At- 
lantic border,  St.  Lawrence  Co.,  N.  Y.,  226,  227;  Mass.,  Conn., 
and  Eastern  K  Y.,  227;  Southeastern  Penn.,  227;  Davison  Co., 
N.  C,  228;  Sullivan  and  Ulster  Counties,  N.  Y.,  228;  Example 
23,  Southeastern  Missouri,  228-231 ;  statistics  of  lead,  232 .226-233 

CHAPTER  VI.— Lead  and  Zinc. 

Example  24,  Upper  Miss.  Valley,  233-237;  Washington  Co., 
Mo.,  238,  239;  Livingston  Co.,  Ky.,  239;  Example  25,  Southwest 
Missouri,  240-245;  Example  26,  Wythe  Co.,  Va.,  247-249 233-249 

CHAPTER  VII. — Zinc  Alone,  or  with  Metals  other  than  Lead. 
Introduction :  Tables  of  analyses  of  zinc  ores,   250 ;  Example 
27,  Saucon  Valley,  Penn.,   250,  251;  Example  28,  Franklin  Fur- 
nace and  Sterling,  N.  J.,  251-257;  Zinc  in  the  Rocky  Mountains, 
258,  259;  in  New  Mexico,  259 250-259 

CHAPTER  VIII.— Lead  and  Silver. 

Introduction,  260;  Rocky  Mountain  region  and  the  Black 
Hills,  260,  274;  New  Mexico,  260-262;  Example  29,  Kelley  Lode, 
260;  Lake  Valley,  260-262;  Colorado,  262-272;  Example  30,  Lead- 

►  ville,  262-266;  Example  30a,  Ten  Mile,  Summit  Co.,  266,  267;  Ex- 
ample 305,  Monarch  District,  ChaifeeCo.,  268;  Example  30c,  Eagle 
River,  Eagle  Co.,  268;  Example  30d,  Aspen,  Pitkin  Co.,  268-271; 
Example 30e,  Rico,  Dolores  Co.,  271,  272;  Example  31,  Red  Moun- 
tain, Ouray  Co.,  272;  South  Dakota,  Example  30/,  272;  Montana- 
Idaho,  Example  32,  Glendale,  273;  Example  32a,  Wood  River,  273; 
Example  33,  Wickes,  Jefferson  Co.,  273;  Example  34,  Coeur 
d'Alene,  274;  Region  of  the  Great  Basin,  274-279;  Utah,  Exam- 
ple 35,  Bingham  and  Big  and  Little  Cottonwood  Canons,  274,  275 ; 
Example  35a,  Tooele  Co,,  275;  Example  355,  Tintic  District, 
275;  Example  30gr,  Hornsilver  Mine,  275,  276;  Example  33a,  Car- 
bonate Mine,  Beaver  Co.,  276;  Example  326,  Cave  Mine,  Beaver 
Co.,  276;  Nevada,  Example  26,  Eureka,  277,  278;  Arizona;  CaU- 
fornia,  279 260-279 

CHAPTER  IX.  —  Silver  and  Gold.  —  Introductory  :  Eastern 
Silver  Mines  and  the  Rocky  Mountain  Region  of  New  Mex- 
ico AND  Colorado. 

Introduction,  280;  Examples  37-42,  defined,  280,  281;  silver 
and  gold  ores,  281-283;  Example  22a,  Atlantic  Border,  283;  Ex- 
ample 42,  Silver  Islet,  Lake  Superior,  283,  284;  Thunder  Bay, 
Canada,  284 ;  region  of  the  Rocky  Mountains  and  the  Black  Hills, 
284-307;  New  Mexico,  geology,  284,  285;  mines,  285,  286;  Colorado, 
geology,  286,  287;  San  Juan  region,  287-293;  Creede  region,  293; 
Gunnison  region,  294;  Eagle  Co.,  294;  Summit  Co.,  294,  295; 
Park,  Chaffee,  Rio  Grande  Counties,  295;  Conejos  Co.,  296;  Cus- 
ter Co.,  296;  Example  39,  Bassick  Mine.  296,  297;  Example  39a, 


xii  TABLE  OF  CONTENTS. 

PAGE 

Bull  Domingo  Mine,  297-299;  Humboldt-Pocahontas,  299;  Silver 
'Cliff,  299,  300;  Teller  Co.,  300-305;    Gilpin  Co.,  305,  306;    Clear 
Creek  Co.,  306;  Boulder  Co.,  306,  307 280-307 

CHAPTER  X.— Silver  and  Gold,  Continued.— Rocky  Mountain 
Region,  Wyoming,  the  Black  Hills,  Montana,  and  Idaho. 

Wyoming,  geology,  308;  South  Dakota,  geology,  309;  the 
Black  Hills,  309-314;  Montana,  geology,  314-316;  Madison  Co., 
316,  317;  Beaverhead  Co.,  317;  Jefferson  Co.,  317,  318;  Silver 
Bow  Co.,  318,  319;  Broadwater  Co.,  319;  Deer  Lodge  Co.,  319; 
Lewis  and  Clarke  Counties,  320;  Meagher  Co.,  320,321;  Cascade 
Co.,  321;  Flathead,  Choteau,  and  Fergus  Counties,  322,  323; 
Idaho,  geology,  323;  Kootenai  and  Lemhi  Counties,  324;  Custer, 
Boise,  Alturas,  and  other  counties,  324-327 308-327 

CHAPTER  XI.— Silver  and  Gold,  Continued.— The  Region  of  the 
Great  Basin,  in  Utah,  Arizona,  and  Nevada. 

Utah,  geology,  328;  Ontario  and  other  mines,  329,  330;  Ex- 
ample 41,  Silver  Reef,  333,  334;  Arizona,  geology,  334;  Apache, 
Yavapai,  Mohave,  Yuma,  Maricopa,  and  Pinal  Counties,  335; 
Silver  King  mine,  335,  336;  Graham  and  Cochise  Counties,  336; 
Tombstone,  336;  Pima  and  Yuma  Counties,  336,  337;  Nevada, 
geology,  337;  Lincoln,  Ney,  and  White  Pine  Counties,  338,  339; 
Lander  and  other  counties,  339,  340;  the  Comstock  Lode,  340- 
345 328-345 

CHAPTER  XIL— The  Pacific  Slope— Washington,  Oregon  and 
California. 

Washington,  geology,  346;  mines,  347;  Oregon  geology,  347, 
348;  Example  44a,  Port  Orford,  348,  349;  California,  geology,  349, 
350;  Calico  District,  351-353;  Example  44,  auriferous  gravels, 
353-362;  river  gravels,  353,  354;  high  or  deep  gravels,  354-360; 
general  resume  of  geological  history  of  gravels,  360-362 ;  Example 
45,  gold-quartz  veins,  362-375 .„....,,,......, 346-375 

CHAPTER  XIII.— Gold  Elsewhere  in  the  United  States  and 
Canada. 

Example  45a,  Southern  Appalachians,  376-378 ;  Alabama,  378, 
379;  Georgia,  379;  South  Carolina,  380;  North  Carolina,  380,  381; 
Virginia,  Maryland  and  the  Northern  States,  381-383;  Example 
45&,  Ishpeming,  Mich.,  383;  the  Rainy  River  District,  383-385; 
Alaska  and  the  Canadian  Northwest,  geology,  385-389 ;  Example 
38,  Douglass  Island,  390-393;  Yukon  Basin,  393-397;  Example  45c, 
Nova  Scotia,  397-399;  gold  elsewhere  in  Canada,  400,  401;  sta- 
tistics, 401,  402 376-400 

CHAPTER  Xrv.— The  Lesser  Metals— Aluminum,  Antimony,  Ar- 
senic, Bismuth,  Chromium,  Manganese. 

Aluminum,  403-410;  antimony,  410,  411;  Example  47,  includ- 
ing California,  Nevada,  Arkansas,  New  Brunswick,  410,  411  r  Ex- 


TABLE  OF  CONTENTS.  xiii 

PAoa 
ample  48,  Iron  Co.,  Utah,  411;  arsenic,  413;  bismuth,  412*  chro- 
mium, 415,  416;  Example  49,  chromite  in  serpentine,  414,  415; 
California,  415,  416;  Quebec,  416;  manganese,  416-423;  Exam 
pie  50,  manganese  ores  in  residual  clay,  418-423 ;  Batesville,  Ark. 
420-422;  Panama,  423 403-433 

CHAPTER   XV.— The   Lesser   Metals,    Continued.— Mercury, 
Nickel  and  Cobalt,  Platinum,  Tin. 

Mercury,  ores,  424,  425 ;  Example  50,  New  Almaden,  425,  426 ; 
Example  50a,  Sulphur  Bank,  427;  Example  50&,  Steam^  3at 
Springs,  Nev.,  427;  resume  regarding  mercuiy,  428;  nickel  and 
cobalt,  428-441 ;  introductory,  428-430 ;  Example  16c,  pyrrhotite 
beds  or  veins,  430,  431;  Example  13a,  Gap  mine,  Penn.,  Sudbury, 
Ont.,  431-438;  Example  49a,  Riddle's,  Oregon,  438-440;  Example 
23a,  Mine  la  Motte,  Mo.,  440;  other  occurrences  of  nickel  ores, 
440,  441;  platinum,  441;  tin,  441,  442;  Example  51,  Black  Hills, 
442,  443;  other  occurrences  of  tin,  443,  444;  Mexico,  444 434-444 

CHAPTER  XVI.— Concluding  Remarks. 

Summation  of  such  general  geological  relations  among  North 
American  ore  deposits  as  can  be  detected 445-447 

APPENDIX  I, — A  Review  of  the  Schemes  for  the  Classification 
OF  Ore  Deposits. 

General  remarks,  447,  448;  schemes  involving  only  the  classification 
of  veins,  448-451 ;  general  schemes  based  on  forms,  451-453 ;  schemes, 
partly  based  on  form,  partly  on  origin,  453-455;  schemes  largely 
based  on  origin,  455-457 ;  schemes  entirely  based  on  origin,  457-459 ; 
remarks  on  schemes  and  classification  of  ore  deposits,  459-462. .  .447-463 


LIST  OF  ILLUSTRATIONS 


FiaS.  PAOB 

1.  Illustration  of  rifting  in  granite  at  Cape  Ann,  Mass.    After  R.  S. 

Tarr 13 

2.  Open  fissure  in  the  Aubrey  limestone  (Upper  Carboniferous),  25 

miles  north  of  Canon  Diablo  Station,  on  the  A.  &  P.  R.R., 
Arizona.     Photographed  by  G.  K.  Gilbert,  1892 0pp.     20 

3.  Normal  fault  at  Leadville,  Colo.     After  A.  A.  Blow 20 

4.  Reversed  fault  at  Holly  Creek,  near  Dalton,  Ga.     After  C.  W. 

Hayes 22 

5.  Illustration  of  an  older  vein,  the  Jiunbo  faulted  by  a  later  one 

(cross  vein)  at  Newman  Hill,  Rico,  Colo.     After  T.  A.  Rickard.     24 

6.  Banded  vein  at  Newman  Hill,  near  Rico,    Colo.     After  J.   B. 

Farish 36 

7.  Map  showing  the  distribution  of  iron  ores  in  North  America 88 

8.  Cross-section  of  the  Prosser  iron  mine  near  Portland,  Ore.,  show- 

ing the  bed  of  limonite  between  two  flows  of  basalt.     After 
B.  T.  Putnam 91 

9.  Section  of  the  Hurst  limonite  bank,  Wj^the  Co.,  Va.,  illustrating 

the  replacement  of  shattered  limestone  with  limonite  and  the 
formation  of  geodes  of  ore.     After  E.  R.  Benton 93 

10.  View  of  the  Low  Moor  limonite  mines,  Virginia.     After  a  photo- 

graph by  J.  F.  Kemp 0pp.     95 

11.  Geological  section  of  the  Low  Moor,  Va.,  iron  ore  bed.     After  B. 

S.  Lyman 96 

12.  Ideal  cross-section  of  Iron  Hill  near  Waukon,  Allamakee  Co., 

Iowa 99 

13.  Geological  section  of  the  Amenia  mine,  Dutchess  Co.,  N.  Y. 

After  B.  T.  Putnam 100 

14.  View  of  the  Siluro- Cambrian,  brown  hematite  bank  at  Baker 

Hill,  Ala.     From  the  Engineering  and  Mining  Journal. .  .0pp.  103 

15.  Map  and  sections  of  the  Burden  spathic  ore  mines.     After  J.  P. 

Kimball. 110 

16.  Clinton  ore,  Ontario,  Wayne  Co.,  N.  Y.     After  C.  H.  Smyth,  Jr.  115 

17.  Clinton  ore,  CUnton,  N.  Y.     After  C.  H.  Smyth,  Jr 116 

18.  Clinton  ore.  Eureka  mine,  Oxmoor,  Ala.     After  C.  H.  Smyth,  Jr.  117 


xvi  LIST  OF  ILLUSTRATIONS. 

FIG.  PAGE 

19.  Cross-section  of  the  Sloss  mine,  Red  Mountain,  Ala.     From  the 

Engineering  and  Mining  Journal 117 

20.  Map  of  the  vicinity  of  Birmingham,  Ala.     From  the  Transac- 

tions of  the  American  Institute  of  Mining  Engineers 119 

21.  View  of  Cherry  Valley  mine,  showing  sandstone  with  underly- 

ing cherty  clay.     After  F.  L,  Nason Opp.  122 

22.  Section  of  the  northern  end  of  the  Cherry  Valley  mine.     After 

F.  L.  Nason Opp.  122 

23.  Cross-section  of  the  Cherry  Valley  mine.     After  F.  L.  Nason .  Opp.  122 

24.  Map  of  the  Lake  Superior  region,  showing  the  location  of  the 

iron-ore  districts.     From  U.  S.  Geological  Survey 126 

25.  Generalized  section  across  Marquette  iron  range,  to  illustrate  the 

type  of  folds.     After  C.  R.  Van  Hise 129 

26.  Geological  map  of  the  western  portion  of  the  Marquette  iron 

range.     After  Van  Hise  and  Bayley 130 

27.  Geological  map  of  the  eastern  portion  of  the  Marquette  iron 

range.     After  Van  Hise  and  Bayley 131 

28.  Cross-section  to  illustrate  the  occurrence  and  associations  of  iron 

ore  in  the  Marquette  district,   Michigan.     After  C.   R.  Van 
Hise = . 133 

29.  Open  cut  in  the  Republic  mine,  Marquette  range,  showing  a 

horse  of  jasper.     After  H.  A.  Wheeler Opp.  133 

30.  Plan  of  the  Ludington  ore  body,  Menominee  district,  Michigan. 

After  P.  Larsson 137 

31.  Geological  map  of  the  Penokee-Gogebic  iron  range.    After  Irving 

and  Van  Hise 140 

32.  Longitudinal  and  cross-section  of  the  Ashland  mine,  Ironwood, 

Mich.,  re-drawn  from  mine  maps 142 

33.  Cross-section  of  the  Colby  mine,  Penokee-Gogebic  district,  Michi- 

gan, to  illustrate  oocurrence  and  origin  of  the  ore.     After  C. 

R.  Van  Hise 143 

34.  Map  of  the  Minnesota  iron  ranges.     After  F.  W.  Denton 145 

85.  Geological  map  of  the  vicinity  of  Tower  and  Soudan,  Minn. 

After  Smyth  and  Finlay 147 

36.  Cross-sections  of  the  ore  bodies  at  Soudan,  Vermilion  Range,  ' 

Minn.     After  Smyth  and  Finlay 149 

37.  Open  cut  at  Minnesota  Iron  Co.'s  mine,  Soudan,  near  Tower,  in 

south  vein,  looking  west.     After  J.  F.  Kemp OpP-  148 

38.  Horizontal  and  vertical  cross-section  of  the  Chandler  ore  body  at 

Ely,  Minn.     After  Smyth  and  Finlay 150 

39.  View  of  Chandler  mine,  showing  sinking  of  ground.     After  J.  F. 

Kemp Opp.  149 

40    General  cross-section  of  ore  body  at  Biwabik,  Mesabi  Range, 

Minn.     After  H.  V.  Winchell IM 

41.  View  of  the  Mesabi  Mountain  or  Oliver  mine,  Virginia,  Minn., 

looking  southeast.     After  J.  F.  Kemp Opp.  153 

42.  Cross-section  of  Pilot  Knob,  Mo.    From  drawing  by  W.  B.  Potter  156 


LIST  OF  ILLUSTRATIONS.  xvii 

FIG.  PAGE 

43.  View  of  open  cut  at  Pilot  Knob,  Mo.,  showing  the  bedded  char- 

acter of  the  iron  ore.     After  J.  F.  Kemp 0pp.  157 

44.  View  of  Iron    Mountain,    Mo.,    from   the    east.     After  H.    A. 

Wheeler 0pp.  158 

45.  Cross-section  of  Iron  Mountain,  Mo.     By  W.  B.  Potter: 156 

46.  View  of  open  cut  and  underground  work  in  mine  21,  Mineville, 

near  Port  Henry,  N.  Y.     After  J.  F.  Kemp 0pp.  163 

47.  Cross-section  of  the  Cheever  iron  mine,  near  Port  Henry,  N.  Y, 

After  J.  F.  Kemp 163 

48.  Geological  map  of  the  iron  mines  at  Mineville,  near  Port  Henry, 

N.  Y.     After  J.  F.  Kemp .163 

49.  Cross-section  of  ore-bodies  at  Mineville,  near  Port  Henry,  N.  Y., 

to  accompany  map,  Fig.  48.     After  J.  F.  Kemp 164 

50  and  51.  Model  of  the  Tilly  Foster  ore  body.     After  F.  S.   Rutt- 

mann  and  J.  F.  Kemp 166 

52.  Sketch  map  illustrating  the  geological  structure  of  the  Hibernia 

magnetite  beds,  Hibernia,  N.  J.     After  J.  E.  Wolff 168 

53.  Section  along  Cornwall  Railroad  from  Lebanon  to  Miner's  Vil- 

lage.    After  E.  V.  dlnvilHers 176 

54.  Map  of  Cornwall  mines.     After  E.  V.  d'Invilliers 177 

55.  Map  of  Ducktown,  Tenn.,  copper  mines,  showing  the  relations 

and  extent  of  the  veins.     After  Carl  Henrich 191 

56.  Cross-section,    shaft  3,    Old  Tennessee  mine,  Ducktown,  lenn. 

After  Carl  Henrich 193 

57.  View  of  the  Mary  Mine,  Ducktown,  Tenn. ,  from  the  west.    From 

a  photograph  by  J.  F.  Kemp 0pp.  194 

58.  Geological  map  of  the  western  half  of  Butte  district,  Montana, 

reproduced  from  map  of  U.  S.  Geological  Survey 198 

59.  Geological  map,  eastern  half,  Butte  district,  Montana.    Idem 199 

60.  View  of  the  Big  Butte,  Butte  City,  Mont.,   looking  northwest 

across  Missoula  Gulch.  From  photograph  by  J.  F.  Kemp.. 0pp.  200 

61.  View  of  the  Anaconda  mine,  Butte,  Mont.     From  photograph  by 

Alexander  Brown Opp-  200 

62.  View  of  the  larger  copper  mines,  Butte,  Mont.,  looking  nearly 

due  east  from  the  roof  of  the  Hotel  Butte.     From  photograph 
by  J.  F.  Kemp .0pp.  201 

63.  Contact  of  the  older  Butte  granite  and  the  later  intruded  Blue- 

bird granite  as  exposed  in  a  cut  on  the  Butte,  Anaconda, 
Pacific  R.  R.     Photographed  by  J.  F.  Kemp 0pp.  202 

64.  Cross-section  of  the  Bob-tail  mines,  Central  City,  Colo.     After  F. 

M.  Endlich 204 

65.  Geological  section  of  Keweenaw  Point,  Mich. ,  near  Portage  Lake 

and  through  Calumet.     After  R.  D.  Irving 206 

66.  Map  of  the  Portage  Lake  district,  Keweenaw  Point,  Mich 207 

67.  Cross-section  in  the  St.  Genevieve  copper  mine,  illustrating  the 

relations  of  the  ore.     After  F.  Nicholson 213 

68.  Section  at  the  St.  Genevieve  mine,  illustrating  the  intimate  re- 

lations of  ore  and  chert.     After  F.  Nicholson 213 


xviii  LIST  OF  ILLUSTRATIONS. 

no.  PAGE 

69.  Geological  map  of  the  Morenci  or  Clifton  copper  district  of 

Arizona.     After  A.  F.  Wendt 214 

70.  Vertical  section  of  Longfellow  Hill,  Clifton  district,  Arizona. 

After  A.  F.  Wendt 215 

71.  Horizontal  section  of  Longfellow  ore  body.     After  A.  F.  Wendt.  215 

72.  Geological  section  of  the  Metcalf  mine,  Clifton  district,  Arizona. 

After  A.  F.  Wendt 216 

73.  View  of  the  Copper  Queen  mine,  Bisbee  district,  Arizona.     From 

photograph  by  James  Douglass 0pp.  218 

74.  Cross-section  of  the  Schuyler  copper  mine,  New  Jersey.     After 

N.  H.  Darton 223 

75.  Geological  map  of  the  Southeastern  Missouri  disseminated  lead 

ore  sub-district.     After  Arthur  Winslow 229 

76.  Gash  veins,  fresh  and  disintegrated.     After  T.  C.  Chamberlin . .  234 

77.  Idealized  section  of  "flats  and  pitches,"  forms  of  ore  bodies  in 

Wisconsin.     After  T.  C.  Chamberlin 235 

78.  Chart  showing  the  results  of  deep  borings  in  the  Joplin  district. 

Mo.     From  Engineering  and  Mining  Journal -. 241 

79.  Vertical  section  of  a  typical  zincblende  ore  body,  near  Webb 

City,  Mo.     After  C.  Henrich 243 

80.  Geological  section  of  the   Bertha  zinc  mine,  Wythe  Co.,  Va. 

After  W.  H.  Case 246 

81.  Geological  section,  Altoona  coal  mines  to  Bertha  zinc  mines. 

After  W.  H.  Case 248 

82.  View  of  open  cut  in  Bertha  zinc  mine,  Va.     Photographed  by  J. 

F.  Kemp 0pp.  248 

83.  View  of  open  cut  in  the  Wythe  zinc  mines,  Va.     Photographed 

by  J.  F.  Kemp Opp.  248 

84.  Cross-section  at  Franklin  Furnace,  N.  J. ,  corresponding  to  AA, 

of  map  (Fig.  88).     At  the  left  is  blue  limestone  and  quartzite. 
After  J.  F.  Kemp 252 

85.  View  of  the  w^est  vein  at  Franklin  Furnace,  looking  south.     The 

two  shafts  are  at  the  Trotter  mine.     Photographed  by  J.  F. 
Kemp Opp.  252 

86.  View  of  the  open  cut  at  south  end  of  Mine  Hill,  Franklin  Fur- 

nace, N.  J.,  exposing  the  syncline  of  ore.     Photographed  by 
J.  F.  Kemp Opp.  253 

87.  View  of  Sterling  Hill,  Ogdensburgh,  N.  J.     From  photograph  by 

J.  F.  Kemp. Opp.  253 

88  and  89.  Geological  map  of  Mine  Hill  and  Sterling  Hill,  showing 

the  relations  of  the  ore  bodies.     After  J.  F.  Kemp 255 

90  and  91.  Stereograms  of  the  ore  bodies  at  Mine  Hill  and  Sterling 

Hill.     After  J.  F.  Kemp 256 

92.  Geological  cross-section  at  Lake  Valley,  New  Mexico,  to  show 

the  relations  of  the  ore.     After  Ellis  Clark 261 

93.  Section  of  the  White  Cap  chute,  Leadville,  showing  the  geo- 

logical relations  of  the  ore,  and  its  passage  into  unchanged 
sulphides  in  depth.     After  A.  A.  Blow 264 


LIST  OF  ILL  U8TBA  TIONS.  xix 

FIG.  PAGE 

94.  Section  through  the  No.  2  ore  chute  of  the  Robinson  mine,  Ten- 

mile  district,  Colo.     After  S.  F.  Emmons 267 

95.  Cross-section,  Queen  of  the  West  mine,  Ten-mile  district,  Colo. 

After  S.  F.  Emmons 267 

96.  Geological  section  at  the  Eagle  River  mines,  Colo.     After  E.  E. 

Olcott 269 

97.  A — Cross-section  of  the  Delia  S.  mine.  Smuggler  Mt. ,  Aspen, 

Colo.     After  J.  E.  Spurr 270 

B — Section  through  the  Durant  and  Aspen  mines.  By  D.  Rohlfing  270 

98.  View  of  the  Bunker  Hill  and  Sullivan  mines,  Wardner,  Idaho. 

Photographed  by  E.  E.  Olcott 0pp.  274 

99.  View  of  town  of  Mammoth,  Tintic  district,  Utah.     Photographed 

by  L.  E.  Riter,  Jr 0pp.  275 

100.  Bullion  and  Beck  mine  and  mill.  Eureka,  Tintic  district,  Utah. 

Photographed  by  L.  E.  Riter,  Jr 0pp.  275 

101.  Section  at  Eureka,  Nev.     After  a  plate  by  J.  S.  Curtis 278 

102.  Geological   sketch  map  of  the  Telluride  district,   Colo.     After 

Arthur  Winslow 289 

103.  Geological  cross-sections  of  strata  and  veins  at  Newman  Hill, 

near  Rico,  Colo.     After  J.  B.  Farish 291 

104.  Geological  cross-sections  of  strata  and  veins  at  Newman  Hill, 

near  Rico,  Colo.     After  J.  B.  Farish 292 

105.  Cross-section  of    the  Bassick  mine,  near  Rosita.      After  S.    F. 

Emmons 298 

106.  Cross-section  of  the  Bull-Domingo  mincj,  near  Silver  Cliff,  Colo. 

After  S.  F.  Emmons 298 

107.  Cross-section  of  the  Humboldt-Pocahontas  vein,   near  Rosita, 

Colo.     After  S.  F.  Emmons 299 

108.  Geological  map  of  Cripple  Creek,  Colo.     U.  S.  Geological  Survey. 

Geology  by  Cross  and  Mattliews 301 

109.  View  of  Cripple  Creek,  Colo.,  from  Mineral  Hill;  Gold  Hill  in 

background.     Photographed  by  J.  F.  Kemp 0pp.  302 

110.  View  of  Battle  Mt.,  Victor,  Colo.,  Portland  group  of  mines  and 

Independence  mine.     Photographed  hy  J.  F.  Kemp 0pp.  802 

111.  Map  of  the  Independence  and  Washington  claims.  Cripple  Creek, 

Colo.     After  R.  A.  F.  Penrose 303 

112.  Stereogram  of  the  Annie  Lee  ore-chute,  Victor,  Colo.     After  R. 

A.  F.  Penrose 304 

113.  Geological  section  of  the  Black  Hills.      After  Henry  Newton 309 

114.  Geological  section   of  the  strata   in  the  Northern  Black  Hills, 

S.  D.     After  John  D.  Irving 310 

115.  Plan  and  crosssection  of  the  Cambrian,   siliceous  gold-ore  de- 

posits in  the  Black  Hills,  S.  D.     After  John  D.  Irving 311 

116.  Plan  and  section.  Mail  and  Express  mine,  to  illustrate  the  sili- 

ceous gold  ores  of  the  Black  Hills,  S.  D.  After  John  D.  Irving.  312 

117.  View  of  Green  Mt.,  Black  Hills,  S.  D.,  a  laccolite  of  phonolite. 


XX  LIST  OF  ILLUSTRATIONS. 

FIG.  PA6B 

with  the  mines  of  siliceous  ore  on  the  so-called  "upper  con- 
tact," around  the  foot.  Photographed  by  John  D.  Irving.  .0pp.  312 

118.  View  of  the  Union  mine  in  siliceous    ore,   near  Terry,  Black 

Hills,  S.  D.     Photographed  by  John  D.  Irving 0pp.  312 

119.  Cross-section  of  a  siliceous  gold  ore-body  lying  next  to  a  porphyry 

dike.  Black  Hills,  S.  D.     After  John  D.  Irving 313 

120.  Prospective  cross-section  of  siliceous  gold  ore-body,  in  Carbonif- 

erous limestone,  Dacy  Flat,  Black  Hills,  S.  D.     After  John  D. 
Irving 0pp.  313 

121.  View  of  the  Golden  Star  open  cut.  Lead  City,  S.  D.     Photo- 

graphed by  J.  F.  Kemp 0pp.  313 

122.  View  of  the  outcrop  of  the  Wabash  silver  lode  projecting  above 

the  granite,  Butte,  Mont.    Photographed  by  A.  C.  Beatty .  .0pp.  318 

123.  View  of  weathered  granite,  Butte,  Mont.     Photographed  by  J. 

F.  Kemp Opp.  318 

124.  Cross-section  of  vein  of  the  Alice  mine,  Butte,  Mont.     After  W. 

P.  Blake 318 

125.  The  old  gold  diggings  on  Napias  Creek,  Leesburg,  Idaho.     Illus- 

trating an  abandoned  placer  camp.     Photographed  by  J.  F. 
Kemp Opp.  324 

126.  View  of  Napias  Creek,  below  California  Bar,  after  a  fre^et. 

Photographed  by  J.  F.  Kemp Opp.  324 

127.  Sections  to  illustrate  typical  gold  veins  in  the  Boise  granite 

"region,  Idaho.     After  W.  Lindgren. 326 

128.  Geological  cross-section  at  Mercur,  Utah.     After  J.  E.  Spurr. . . .  330 

129.  Diagram  showing  relations  of  ore  to  fault  in  Tunnel  No.  3,  Mar- 

ion mine,  Mercur,  Utah.     After  J.  E.  Spurr 331 

130.  Section  along  the  Geyser  mine  tunnel,  Mercur,  Utah.     After  J. 

E.  Spurr : 331 

131.  View  of  open  cut,  showing  pay  streak  at  Mercur,  Utah.     From  a 

photograph  by  P.  K.  Hudson Opp.  332 

132.  The  Golden  Gate  cyanide  mill,  Mercur,  Utah.     From  a  photo- 

graph by  L.  E.  Eiter,  Jr Opp.  332 

133.  Two  sections  of  the  argentiferous  sandstone  of  Silver  Reef,  Utah. 

After  C.  M.  Rolker 333 

134.  Section  of  the  Comstock  Lode  on  the  line  of  Sutro  tunnel.    After 

G.  F.  Becker 341 

135.  Geological  section  of  the  Calico  district,  California.     After  W. 

Lindgren 351 

136.  View  of  the  Randsburg,  California,  looking  southeast.     Schists 

underlie  the  town,  but  the  hills  are  eruptive.     From  a  photo- 
graph by  H.  A.  Titcomb Opp.  350 

137.  View  of  the  Stevens  hydraulic  placer  mine,  Auro  City,  Colo. 

From  a  photograph Opp-  350 

138.  View  in  the  Malakoff  hydraulic  placer  mine,  North  Bloomfield, 

Calif.     From  a  photograph Opp.  351 

139.  View  of  the  Malakoff  hydraulic  placer  mine.  North  Bloomfield, 

Calif.     From  a  photograph OpP-  ^51 


LIST  OF  ILLUSTRATIONS.  xxi 


FIG, 


PAGE 

140.  Generalized  section  of  a  deep  gravel  bed,  with  technical  terms. 

After  R.  E.  Browne = 355 

141.  Section  of  Forest  Hill  Divide,  Placer  Co.,  Calif.,  to  illustrate  the 

relations  of  old  and  modern  lines  of  drainage.     After  R.  E. 
Browne - • 356 

142.  North  Star  vein.  Grass  Valley,   Calif.,   showing  quartz  vein  in 

brecciated  and  altered  diabase.     After  W.  Lindgren 0pp.  363 

143  and  144.  Ore  shoots  of  Nevada  City  and  Grass  Valley  mines,  Calif. 

After  W.  Lindgren. 364 

145.  Section  of  the  Pittsburg  vein,  ninth  level,  Nevada  City  district, 

Calif.     From  U.  S.  Geological  Survey 365 

146.  Geological  section  at  Merrifield  vein.  Providence  claim,  Nevada 

City  district,  Cahf.     After  W.  Lindgren. 366 

147.  Cross-section  of  vein  in  St.  John  mine,  fifth  level,  Nevada  City 

district,  Calif.     After  W.  Lindgren. , .  „ 366 

148.  Cross-section  of  the  Maryland  vein,  in  slope  above  1500-foot  level. 

Grass  Valley  district,  Calif.    After  W.  Lindgren , . .  367 

149.  Cross-section  of  the  Brunswick  vein,  on  the  700-foot  level.  Grass 
Valley  district,  Calif.     After  W.  Lindgren 368 

150.  Western  half  of  Geological  map  of  the  Yukon  Gold  Belt,  and  ad- 

jacent regions.     (See  Fig.  151) 386 

151.  Eastern  half  of  Geological  map  of  the  Yukon  Gold  Belt,  and  ad- 

jacent regions.     After  J.  E,  Spurr 387 

152.  Map  of  the  Juneau  mining  district,  Southeast  Alaska.     After  G. 

F.  Becker 392 

153.  Sketch  map  of  Nova  Scotia  Gold  Fieldc.     After  E.  Gilpin. 398 

154.  Cross-section  of  a  Bauxite  deposit  in  Georgia.     After  C.  Willard 

Hayes , » 405 

155.  Sections  of  the  Crimora  manganese  mine,  Virginia.     After  C.  E. 

Hall 418 

156.  Geological  sections  illustrating  the  formation  oi  manganese  ores 

in  Arkansas.     After  R,  A.  F.  Penrose 419 

157.  The  Turner  mine,  Batesville  region,  Arkansas.     After  R.  A.  F 

Penrose « .  = . .  420 

158.  Section    of   the  Great  Western    cinnabar  mine.    After  G.  F 

Becker , . , , .  426 

159.  Map  and  section  of  Gap  Nickel  mine,   Lancaster  Co.,  Penn. 

After  J.  F.  Kemp , 433 

160.  Geological  section-map  of  the  Sudbury  .district,  Ontario.     After 

by  T.  L.  Walker. , , 435 

161  and  162.  View  of  Copper  Cliff  mine,  Sudbury,  Ontario.     Photo- 
graphs by  T.  G.  White 0pp.  436 

163.  Horizontal  section  of  the  Etta  granite  knob,  Black  Hills,  S.  D. 

After  W.  P.  Blake , 442 


ABBREVIATIONS 


Amen  Assoc.  Adv.  Sci.,  or  A.  A.  A.  >S.— Proceedings  of  the  American  As- 
sociation for  the  Advancement  of  Science. 
Amer.  Geol. — American  Geologist.     Minneapolis,  Minn. 
Amer.  Jour.  Sci. — American  Journal  of  Science,  also  known  as  Silliman's 

Journal.     Fifty  half-  yearly  volumes  make  a  series.     The  Journal  is 

now  (1893)  in  the  third  series.     In  the  references  the  series  is  given 

first,  then  the  volume,  then  the  page. 
Ann.  des  Mines — Annales  des  Mines.     Paris,  France. 
Bost.  Soc.  Nat.  Hist. — See  Proceedings  of  same. 

Bull.  Geol.  Soc.  Amer. — Bulletin  of  the  Geological  Society  of  America. 
Bidl.  Mus.  Comp.  Zool. — Bulletin  of  the  Museum  of  Comparative  Zoology, 

Harvard  University.     Cambridge,  Mass. 
B.    und  H.    Zeitung. — Berg-  und  Huettenmdnnische  Zeitung.     Leipzig, 

Germany. 
Neues  Jahrb. — Neues  Jahrbuch  fiir  Mineralogie,  Geologie  und  Palseon- 

tologie,  often  called  Leonhard's  Jahrbuch.     Stuttgart,  Germany. 
Oest.  Zeit.  f.  Berg.  u.  Huett.  — Oesterreichische  Zeitschrift  fur  Berg-  und 

Huettenwesen.     Vienna,  Austria. 
Philos.  Mag. — Philosophical  Magazine.       Edinburgh,  Scotland. 
Proc.  Amer.  Acad.  — Proceedings  of  the  American  Academy  of  Arts  and 

Sciences.     Boston,  Mass. 
Proc.  and  Trans.  N.  S.  Inst.  Nat.  Sci. — Proceedings  and  Transactions  of 

the  Nova  Scotia  Institute  of  Natural  Science.     Halifax,  Nova  Scotia. 
Proc.  Bost.  Soc.  Nat.  Hist. — Proceedings  of  the  Boston  Society  of  Natural 

History.     Boston,  Mass. 
Proc.   Colo.  Sci.  Soc. — Proceedings  of  the  Colorado  Scientific  Society. 

Denver,  Colo. 
Raymond's  Reports. — Mineral  Resources  West  of  the  Rocky  Mountains, 

Washington,  1867-1876.     The  fij'st  two  volumes  were  edited  by  J.  Ross 

Browne,  the  others  by  R.  W.  Raymond. 
Trans.  Amer.  Inst.  Min.  Eng. — Transactions  of  the  American  Institute  of 

Mining  Engineers. 
Trans.  Min.  Assoc,  and  Inst.,  Cornwall. — Transactions  of  the  Mining  As- 
sociation and  Institute  of  Cornwall.     Tuckingmill,  Camborn,  England. 


xxiv  ABBRE  VIA  TIONS. 

Trans.  N.  Y.  Acad,  of  Sci. — Transactions  of  the  New  York  Academy  of 

Sciences,  formerly  the  Lyceum  of  Natural  History. 
Zeit.  d.  d.  g.   Ges. — Zeitschrift  der  deutschen  geologischen  Gesellschaft. 

Berlin,  Germany. 
Zeitsch.  f.  B.,  H.  und  S.  im.  P.  St. — Zeitschrift  fur  Berg-,  Huetten-,  und 

Salinenwesen  im  Preussischen  Staat.     Berlin,  Germany. 
Zeitschr.  f.  Krys. — Zeitschrift  fiXr  KrystallograpMe.     Munich,  Germany. 
Zeitsch  f.  prakt.  Geol. — Zeitschrift  fiir  praktische  Geologie.     Berlin,  Ger- 
many. 

The  remaining  abbreviations  are  deemed  self-explanatory.  The  num- 
bering of  the  paragraphs  is  on  the  following  principle:  The  first  digit 
refers  invariably  to  the  part  of  the  book,  the  second  digits  to  the  chapter, 
and  the  last  two  to  the  paragraph  of  the  chapter. 


PART  I. 

INTRODUCTORY. 


CHAPTER  I. 

GENERAL  GEOLOGICAL  FACTS   AND   PRINCIPLES. 

1.01.01/  In  the  advance  of  geological  science  the  stand- 
points from  which  the  strata  forming  the  earth's  crust  are  re- 
garded necessarily  change,  and  new  points  of  view  are  estab- 
lished. In  the  last  few  years  two  have  become  especially 
prominent,  and  there  are  now  two  sharply  contrasted  positions 
from  which  to  obtain  a  conception  of  the  structure  and  develop- 
ment of  the  globe.  The  first  is  the  physical,  the  second  the 
biological.  For  example,  we  consider  the  surface  of  the  earth 
as  formed  by  rocks,  differing  in-  one  part  and  another,  and 
these  different  rocks  or  groups  of  rocks  are  known  by  different 
names.  The  names  have  no  special  reference  to  the  animal 
remains  found  in  them,  but  merely  indicate  that  series  of  re- 
lated strata  form  the  surface  in  particular  regions.  On  the 
other  hand,  the  rocks  are  also  regarded  as  having  been  formed 
in  historical  sequence,  and  as  containing  the  remains  of  organ- 
isms characteristic  of  the  period  of  their  formation.  They  illus- 
trate the  development  of  animal  and  vegetable  life,  and  in  this 
way  afford  materials  for  historical-biological  study.  In  the 
original  classification,  the  biological  and  historical  considera- 
tions are  all-important.  But  when  once  the  rocks  are  placed  in 
their  true  position  in  the  scale,  and  are  named,  these  considera- 
tions, for  many  purposes,  no  longer  concern  us.  The  forma- 
tions are  regarded  simply  as  members  in  the  physical  constitu- 
tion of  the  outer  crust.  The  International  Geological  Congress 
held  in  Berlin  in  1885  expressed  these  different  points  of  view 
in  two  parallel  and  equivalent  series  of  geological  terms,  which 

^  The  numbers  at  the  b^inning  of  the  paragraphs  are  so  arranged  that 
the  first  figure  denotes  the  part  of  the  book,  the  next  two  figures  the  chap- 
ter, and  the  last  two  the  paragraph.  Thus  1.06.21  means  Part  I.,  Chapter 
VI.,  Paragraph  21  under  Chapter  VI. 


KEMP'S  ORE  DEPOSITS. 


are  tabulated  on  p.  4.  They  are  now  very  generally  adopted. 
For  clearness  in  illustration,  the  equivalent  terms  employed  by 
Dana  are  appended. 


Biological  Terms. 

Physical  Terms. 

Dana's  Terms. 

niustrations. 

Era. 

Group. 

Time. 

Paleozoic. 

Period. 

System. 

Age. 

Devonian. 

Epoch. 

Series. 

Period. 

Hamilton. 

Age. 

Stage. 

Epoch. 

Marcellus. 

The  United  States  Geological  Survey  divides  as  follows :  Era 
and  System,  Period  and  Group,  Epoch  and  Formation.  In 
considering  the  ore  deposits  of  the  country,  we  employ  only  the 
physical  terms.  We  understand,  of  course,  the  chronological 
position  of  the  systems  in  historical  sequence,  but  it  is  of  small 
moment  in  this  connection  what  may  be  the  forms  of  life  in- 
closed in  them.  The  purely  physical  character  of  the  rocks — 
.whether  crystalline  or  fragmental;  whether  limestone,  sand- 
stone, granite  or  schists;  whether  folded,  faulted,  or  undis- 
turbed— are  the  features  on  which  we  lay  especial  stress.  In 
all  the  periods  the  same  sedimentary  rocks  are  repeated,  and 
in  the  hand  specimen  it  is  almost  always  impossible  to  distin- 
guish those  of  different  ages  from  one  another.  The  classifi- 
cation, briefly  summarized,  is  as  follows : 

1.01.02.  Archean  Group.— I.  Laurentian  System.  II. 
Huronian  System.  Additional  subdivisions  have  been  intro- 
duced by  Canadian  and  Minnesota  geologists  (Animikie,  Mont- 
alban,  etc.),  and  it  is  a  growing  custom  to  call  all  those  which 
are  sediments  or  later  than  sediments,  especially  in  the  region 
of  the  Great  Lakes,  by  the  name  of  Algonkian.  (See  discus- 
sion under  Example  9.) 

Paleozoic  Group. — III.  Keweenawan  System.  (This 
may  belong  with  the  Archean.)  IV.  Cambrian  System:  (a) 
Georgian  Stage;  (6)  Acadian  Stage;  (c)  Potsdam  Stage.  V. 
Lower  Silurian  System.  (A)  Canadian  Series:  (a)  Calcifer- 
ous  Stage;  (b)  Chazy  Stage.  (This  will  probably  experience 
revision.)  (B)  Trenton  Series:  (a)  Trenton  Stage;  (b)  Utica 
Stage;  (c)  Cincinnati  or  Hudson  River  Stage.  VI.  Upper 
Silurian  System.  (J.)  Niagara  Series:  (a)  Medina  Stage;  (b) 
Clinton  Stage;  (c)  Niagara  Stage.  (B)  Salina  Series.  (C) 
Lower  Helderberg  Series.  VII.  Devonian  System.  (A)  Oris- 
kany  Series.     (B)  Corniferous  Series;    (a)  Cauda-Galli  Stage. 


GENERAL  QEOLOGIGAL  FACTS  AND  PRINCIPLES.  5 

(h)  Schoharie  Stage;  (c)  Corniferous  Stage.  ((7)  Hamilton 
Series:  (a)  Marcellus  Stage;  (6)  Hamilton  Stage;  (c)  Genesee 
Stage.  (Z>)  Chemung  Series:  (a)  Portage  Stage;  (6)  Chemung 
Stage.  VIII.  Carboniferous  System.  {A)  Sub-carboniferous 
or  Mississippian  Series.  {B)  Carboniferous  Series.  (C) 
Permian  Series. 

Mesozoic  Group. — IX.  Triassic  Sj'stem.  X.  Jurassic  Sys- 
tem. IX.  and  X.  are  not  sharply  divided  in  the  United  States, 
and  we  often  speak  of  Jura-Trias.  A  stratum  of  gravel  and 
sand,  along  the  Atlantic  coast,  that  contains  Jurassic  fossils 
has  been  called  the  Potomac  formation  by  McGee.  XI.  Cre- 
taceous System.  Subdivisions  differ  in  different  parts  of  the 
country.  Atlantic  Border:  (a)  Karitan  Stage;  (6)  New  Jer- 
sey Greensand  Stage,  Gulf  States:  (a)  Tuscaloosa  Stage;  (6) 
Eutaw  Stage;  (c)  Rotten  Limestone  Stage ;  (d)  Ripley  Stage. 
Rocky  Mountains:  {a)  Comanche  Stage;  {h)  Dakota  Stage;  (c) 
Benton  Stage;  (d)  Niobrara  Stage;  (e)  Pierre  Stage;  (/)  Fox 
Hills  Stage;  {g)  Laramie  Stage,  Stages  (c)  and  (d)  are 
sometimes  collectively  called  the  Colorado  Stage;  while  (e) 
and  (/)are  grouped  as  the  Montana  Stage.  Pacific  Coast:  (a) 
Shasta  Stage ;  (6)  Chico  Stage, 

Cenozoic  Group. — XII.  Tertiary  System.  Gulf  States. 
{A)  Eocene  Series:  Midway,  Lignitic,  Lower  Claiborne,  Clai- 
borne, Jackson  and  Vicksburg  Stages.  (J5)  Oligocene,  want- 
lug.  (C)  Miocene  Series,  Chattahoochee,  Chipola  and  Chesa- 
peake Stages.  {!))  Pliocene  Series:  Floridian  Stage.  Interior 
Region.  {A)  Eocene  Series :  Puerco,  Torrejon,  Wasatch,  Wind 
River,  Bridger  and  Uinta  Stages.  {B)  Oligocene  Series:  White 
River  Stage.  (C)  Miocene  Series:  John  Day,  Deep  River, 
and  Loup  Fork  Stages.  {D)  Pliocene  Series:  Good-night 
(Palo  Duro)  and  Blanco  Stages.  Pacific  Coast.  The  Eocene 
is  called  the  Tejon.  Miocene  and  Pliocene  are  used  for  the 
others. 

XIII.  Quaternary  System.  {A)  Glacial  Series.  {B) 
Champlam  Series.  (C)  Terrace  Series.  (X))  Recent  Series, 
Pleistocene  is  sometimes  employed  as  a  name  for  the  early 
Quaternary,  especially  south  of  the  Glacial  Drift.  In  accord 
witb  the  practice  of  the  U.  S.  Geological  Survey,  the  Tertiary 
is  now  generally  divided  into  the  Eocene  and  the  Neocene  (in- 
cluding Ohgocene'  Miocene  and  Pliocene)  series. 


6  KEMP'S  ORE  DEPOSITS. 

Other  terms  are  also  often  used,  especially  when  we  do  not 
wish  to  speak  too  definitely.  ** Formation"  is  a  word  loosely 
employed  for  any  of  the  above  divisions.  ''Terrane"  is  used 
much  in  the  same  way,  but  is  rather  more  restricted  to  the 
lesser  divisions.  A  stratum  is  one  of  the  larger  sheet- like 
masses  of  sedimentary  rock  of  the  same  kind;  a  bed  is  a 
thinner  subdivision  of  a  stratum.  **Horizon"  serves  to  indi- 
cate a  particular  position  in  the  geological  column;  thus, 
speaking  of  the  Marcellus  Stage,  we  say  that  shales  of  this 
horizon  occur  in  central  New  York. 

1.01.03.  The  rock  species  themselves  are  classified  into 
three  great  groups — the  Igneous,  the  Sedimentary,  and  the 
Metamorphic. 

The  Igneous  (synonymous  terms,  in  whole  or  in  part :  massive, 
eruptive,  volcanic,  plutonic)  include  all  those  which  have 
solidified  from  a  state  of  fusion.  They  are  marked  by  three 
types  of  structure — the  granitoid,  the  porpbyritic,  and  the 
glassy,  depending  on  the  circumstances  under  which  they 
have  cooled.  Under  the  first  type  of  structure  come  the 
granites,  syenites,  diorites,  gabbros,  diabases,  and  peri- 
dotites;  under  the  second,  quartz-porphyries,  rhyolites,  por- 
phyries, trachytes,  porphyrites,  andesites,  and  basalt;  under 
the  third,  pitchstone,  obsidian,  and  other  glasses. 

The  Sedimentary  rocks  are  those  which  have  been  deposited 
in  water.  They  consist  chiefly  of  the  fragments  of  pre-existing 
rocks  and  the  remains  of  organisms.  They  include  gravel, 
conglomerate,  breccia,  sandstone — both  argillaceous  and  cal- 
careous—shales, clay,  limestone,  and  coal.  In  volcanic  dis- 
tricts, and  especially  where  the  eruptions  have  been  subma- 
rine, extensive  deposits  of  volcanic  lapilli  and  fine  ejectments 
have  been  formed,  called  tuffs.  With  the  sedimentary  rocks  we 
place  a  few  that  have  originated  by  the  evaporation  of  solu- 
tions, such  as  rock  salt,  gypsum,  etc. 

The  Metamorphic  rocks  are  usually  altered  and  crystallized 
members  of  the  sedimentary  series,  but  igneous  rocks  are 
known  to  be  subject  to  like  change,  especially  when  in  the 
form  of  tuffs.  They  are  all  more  or  less  crystalline,  more  or 
less  distinctly  bedded  or  laminated,  of  ancient  geological  agec 
or  in  disturbed  districts.  They  include  gneiss,  crystalline 
schists,  quartzite,  slate,  marble,  and  serpentine. 


GENERAL  GEOLOGICAL  FACTS  AND  PRINCIPLES.  7 

After  a  brief  topographical  survey,  we  shall  employ  the 
above  terms  to  summarize  the  geological  structure  of  the 
United  States.  The  several  purely  artificial  territorial  divi- 
sions are  made  simply  for  convenience.  Nothing  but  intelli- 
gent travel  will  perfectly  acquaint  one  with  the  topographical 
and  geological  structure  of  the  country,  and  in  this  connection 
Macfarlane's  "Geological  Railway  Guide"  and  a  geological 
map  are  indispensable. 

1.01.04.  On  the  east  we  note  the  great  chain  of  the  Appa- 
lachians, with  a  more  or  less  strongly  marked  plain  between  it 
and  the  sea.  This  is  especially  developed  in  the  south,  and  is 
now  generally  called  the  Coastal  Plain.  It  is  of  late  geologi- 
cal age,  and  contains  the  pine  barrens  and  seacoast  swamps. 
The  Appalachians  themselves  consist  of  many  ridges,  running 
on  the  north  into  the  White  Mountains,  the  Green  Mountains, 
and  the  Adirondacks.  Farther  south  the  Highlands  of  New 
York  and  New  Jersey,  the  South  Mountain  of  Pennsylvania, 
the  Alleghenies,the  Blue  Ridge,  and  the  other  southern  ranges 
make  up  the  great  eastern  continental  mountain  system.  In 
western  New  York  and  Ohio  we  find  a  rolling,  hilly  country; 
in  Kentucky  and  Tennessee,  elevated  tableland,  with  deeply 
worn  river  valley's.  Indiana,  Illinois,  Iowa,  and  Missouri  con- 
tain prairie  and  rolling  country,  more  broken  in  southern  Mis- 
souri by  the  Ozark  uplift.  In  Michigan,  Wisconsin,  and  Minne- 
sota, the  surface  is  rolling  and  hilly  with  numerous  lakes.  In 
Arkansas,  Louisiana,  and  Mississippi  there  are  bottom  lands 
along  the  Mississippi  and  Gulf  with  low  hills  back  in  the  interior. 
Across  Arkansas  and  Indian  Territory  runs  the  east  and  west 
Ouachita  uplift.  West  of  these  States  comes  the  region  of 
the  great  plains,  and  then  the  chain  of  the  Rocky  Mountains, 
consisting  of  high,  dome-shaped  peaks  and  ridges,  with  ex- 
tended elevated  valleys  (the  parks)  between  the  ranges.  Some 
distance  east  of  the  main  chain  are  the  Black  Hills,  made  up 
of  later  concentric  formations  around  a  central,  older  nucleus. 
To  the  east  lies  also  the  extinct  volcanic  district  of  the 
Yellowstone  National  Park.  In  western  Colorado,  Utah, 
and  New  Mexico,  between  the  Rocky  Mountains  and  the 
Wasatch,  is  the  Colorado  plateau,  an  elevated  tableland. 
This  is  terminated  by  the  north  and  south  Wasatch  range, 
and  is  traversed  east  and  west  by  the  Uintah  range.     To  the 


8  KEMP'S  ORE  DEPOSITS. 

west  lies  the  region  called  the  Great  Basin,  characterized  by- 
alkaline  deserts,  and  subordinate  north  and  south  ranges  of 
mountains.  Next  comes  the  chain  of  the  Sierra  Nevada,  and 
lying  between  it  and  the  Coast  range  is  the  great  north  and 
south  valley  of  California.  This  rises  in  the  comparatively 
low  Coast  range,  which  slopes  down  to  the  Pacific  Ocean. 
To  the  north,  these  mountains  extend  into  eastern  Oregon 
and  Washington,  with  forests  and  fertile  river  valleys. 
These  topographical  features  are  important  in  connection 
with  what  follows,  for  the  reason  that  the  ore  deposits 
especially  favor  mountainous  regions.  Mountains  them- 
selves are  due  to  geological  disturbances — upheaval,  folding, 
faulting,  etc. — and  are  often  accompanied  by  great  igneous 
outbreaks.  They  therefore  form  the  topographical  surround- 
ings most  favorable  to  the  development  of  cavities,  waterways, 
and  those  subterranean,  mineral-bearing  circulations  which 
would  fill  the  cavities  or  replace  the  rock  with  useful  min- 
erals. 

1.01.05.  Geological  Outline,  I.  New  EnglancL,  New  York, 
New  Jersey,  and  Eastern  Pennsylvania  District. — In 
New  England  and  northern  New  York  the  Archean  is  espe- 
cially developed,  forming  the  White  Mountains,  the  Adiron- 
dacks,  and  the  Highlands  of  New  York  and  New  Jersey. 
These  all  consist  of  granite  and  other  igneous  rock,  of  gneiss, 
and  of  crystalline  schists.  There  are  also  great  areas  of  meta- 
morphic  rocks  whose  true  age  may  be  later.  The  Green  Moun- 
tains are  formed  of  such,  and  were  elevated  at  the  close  of  the 
Lower  Silurian.  In  New  England  there  are  small,  scattered 
exposures  of  the  undoubted  Paleozoic  (Devonian,  Carbonif- 
erous). In  eastern  New  York,  and  to  some  extent  in  New  Jer- 
sey and  eastern  Pennsylvania,  the  entire  Paleozoic,  except  the 
Carboniferous,  is  strongly  developed.  Up  and  down  the  coast 
there  are  narrow  north  and  south  estuary  deposits  of  red  Jura- 
Trias  sandstone,  which  are  pierced  by  diabase  eruptions.  The 
Cretaceous  clays  are  strong,  and  the  Tertiary  strata  occur  at 
Martha's  Vineyard,  in  Massachusetts,  while  over  all,  as  far 
south  as  Trenton,  is  found  the  glacial  drift.  Between  the 
Archean  ridges  of  the  Highlands,  and  the  first  foldings  of  the 
Paleozoic  on  the  west  is  found  the  so-called  Great  Valley, 
which  also  runs  to  the  south  and  is  a  very  important  topo- 


GENERAL  GEOLOGICAL  FACTS  AND  PRINCIPLES.  9 

graphic  and  geologic  feature.     It  follows  the  outcrop  of  the 
Siluro-Cambrian  limestones,  to  whose  erosion  it  is  due. 

II.  Eastern -Middle  and  Southeastern  Coast  District. — 
The  low  plains  of  the  coast  are  formed  by  Quaternary,  Terti- 
ary, and  Cretaceous,  consisting  of  gravel,  sand,  shell  beds,  and 
clay.  Inland  there  are  exposures  of  Jura- Trias,  as  in  the 
north.  The  Archean  crystalline  rocks  are  also  seen  at  numer- 
ous points  not  far  from  the  ocean.  Florida  is  largely  made 
up  of  limestones,  with  a  mantle  of  calcareous  sand. 

III.  Allegheny  Region  and  the  Central  Plateau. — The 
Appalachian  mountain  system,  from  New  York  to  Alabama, 
consists  principally  of  folded  Paleozoic  (largely  Carboniferous), 
with  Archean  ridges  on  its  eastern  flank.  There  is  an  enor- 
mous development  of  folds,  with  northeast  and  southwest  axes. 
On  the  west  they  are  succeeded  by  the  plateau  region  of  Ken- 
tucky and  Tennessee,  chiefly  Paleozoic.  Along  central  latitudes 
the  Archean  does  not  appear  again  east  of  the  Mississippi. 

IV.  Region  of  the  Great  Lakes. — In  Michigan,  Wiscon- 
sin, and  Minnesota  the  Archean  rocks  are  extensively  devel- 
oped, both  Laurentian  and  Huron ian.  Around  Lake  Superior 
are  found  the  igneous  and  sedimentary  rocks  of  the  Keweena- 
wan,  followed  by  the  lower  Paleozoic.  Lake  Michigan  and 
Lake  Huron  are  surrounded  by  Silurian,  Devonian,  and  Car- 
boniferous; Lake  Erie  by  Devonian;  Lake  Ontario,  by  Silu- 
rian. Running  south  through  Ohio,  we  find  an  important  fold 
known  as  the  Cincinnati  uplift,  with  a  north  and  south  axis. 
It  was  elevated  at  the  close  of  the  Lower  Silurian.  In  the 
lower  peninsula  of  Michigan  and  in  eastern  Ohio  and  western 
Pennsylvania  the  Carboniferous  is  extensively  developed. 

V.  Mississippi  Valley. — The  headwaters  of  the  Mississippi 
are  in  the  Archean,  It  then  passes  over  Cambrian  and  Silu- 
rian strata  in  Minnesota.  Wisconsin,  northern  Iowa,  and  Illi- 
nois, which  in  these  States  lie  on  the  flanks  of  the  Archean 
''Wisconsin  Island"  of  central  Wisconsin.  These  are  suc- 
ceeded by  subordinate  Devonian,  and  in  Southern  Iowa,  Illi- 
nois, and  Missouri  by  Carboniferous.  In  southern  Missouri 
the  Lower  Silurian  forms  the  west  bank.  Thence  to  the  Gulf 
the  river  flows  on  estuary  deposits  of  Quaternary  age,  with 
Tertiary  and  Cretaceous  farther  inland. 

VI.  The  Gulf  Region. — The   Gulf  States  along  the  water 


10  KEMP'S  ORE  DEPOSITS. 

front  are  formed  by  the  Quaternary.  This  is  soon  succeeded 
inland  by  very  extensive  Tertiary  beds,  which  are  the  princi- 
pal formation  represented. 

VII.  The  Great  Plains. — West  of  the  Paleozoic  rocks  of 
the  States  bordering  on  the  Mississippi  is  found  a  broad  strip 
of  Cretaceous  running  from  the  Gulf  of  Mexico  to  and  across 
British  America,  and  bounded  on  the  west  by  the  foothills  of 
the  Rocky  Mountains.  A  few  Tertiary  lake  deposits  are  found 
in  it.  Quite  extensive  Triassic  rocks  are  developed  on  the 
south.  The  surface  is  a  gradually  rising  plateau  to  the  Rocky 
Mountains. 

VIII.  Region  of  the  Rocky  Mountains^  the  Black  Hills, 
and  the  Yellowstone  National  Park,  The  Rocky  Mountains 
rise  from  the  prairies  in  long  north  and  south  ranges,  consist- 
ing of  Archean  or  Algonkian  axes  with  the  Paleozoic  in 
relatively  small  amount  in  Colorado,  but  present  in  a  large  cross- 
section  in  Montana.  There  is  abundant  Mesozoic  on  the  east 
and  west  flanks.  In  the  parks  are  found  lake  deposits  of  Ter- 
tiary age.  There  are  also  great  bodies  of  igneous  rocks,  which 
attended  the  various  upheavals.  The  principal  upheavals 
began  at  the  close  of  the  Cretaceous.  The  outlying  Black 
Hills  consist  of  an  elliptical  Archean  core,  with  concentric 
Paleozoic  and  Mesozoic  strata  laid  up  around  it.  The 
National  Park  consists  chiefly  of  igneous  (volcanic)  rocks  in 
enormous  development. 

IX.  Colorado  Plateau, — The  Rocky  Mountains  shade  out 
on  the  west  into  a  great  elevated  plateau,  extending  to  central 
Utah,  where  it  is  cut  off  by  the  north  and  south  chain  of  the 
Wasatch.  The  Uintah  Mountains  are  an  east  and  west  chain 
in  its  northern  portion.  The  rocks  on  the  north  are  chiefl}^  Terti- 
ary, with  Mesozoic  and  Paleozoic  in  the  mountains.  To  the 
south  are  found  Cretaceous  and  Triassic  strata,  with  igneous 
rocks  of  great  extent.  The  principal  upheaval  of  the  Wasatch 
began  at  the  close  of  the  Carboniferous,  and  seems  still  to  be  in 
progress. 

X.  Region  of  the  Great  Basin, — Between  the  Wasatch 
and  the  Sierra  Nevada  ranges  is  found  the  Great  Basin  region, 
once  lake  bottoms,  now  very  largely  alkaline  plains  of  Qua- 
ternary age.  The  surface  is  diversified  by  subordinate  north 
and  south  ranges,  formed  by  great  outflows  of  eruptive  rocks, 


GENERAL  GEOLOGICAL  FACTS  AND  PRINCIPLES.        H 

and  by  tilted  Paleozoic.  The  ranges  are  extensively  broken  and 
the  stratified  rocks  often  lie  in  confused  and  irregular  positions. 
There  is  no  drainage  to  the  ocean. 

XI.  Region  of  the  Pacific  Slope. — The  depression  of  the 
Great  Easin  is  succeeded  by  the  heights  of  the  Sierra  Nevada. 
On  the  west  the  Sierras  slope  down  into  the  Central  Valley  of 
California.  The  flanks  are  largely  nietamorphosed  Jurassic 
and  Cretaceous  rocks  with  great  developments  of  igneous  out- 
flows. The  surface  rises  again  in  the  Coast  ranges,  which  slope 
away  farther  west  to  the  ocean.  In  addition  to  the  Jurassic 
and  Cretaceous,  the  Tertiary  and  Quaternary  are  also  devel- 
oped, and  in  the  Coast  ranges  are  many  outflows  of  igneous 
rock.  The  principal  upheaval  of  the  Sierra  Nevada  began  at 
the  close  of  the  Jurassic,  that  of  the  Coast  range  at  the  close 
of  the  Miocene  Tertiary. 

XII.  Region  of  the  Northwest. — Washington  and  Oregon, 
along  the  coast,  are  formed  by  Cretaceous  and  Tertiary  strata 
similar  to  California.  But  inland,  immense  outpourings  of 
igneous  rocks  cover  the  greater  portion  of  both  States  and  ex- 
tend into  Idaho.  On  the  north  the  Carboniferous  is  extensive, 
running  eastward  into  Montana.  Quaternary  and  Tertiary 
lake  deposits  are  also  not  lacking. 

1.01.06.  On  the  Forms  Assumed  by  Rock  Masses. — All 
sedimentary  rocks  have  been  orginally  deposited  in  beds,  ap- 
proximately horizontal.  They  are  not  of  necessity  absolutely 
horizontal,  because  they  may  have  been  formed  on  a  sloping  bot- 
tom, or  in  a  delta,  in  both  of  which  cases  an  apparent  dip  ensues. 
We  find  them  now,  however,  in  almost  all  cases  changed  from 
a  horizontal  position  by  movements  caused  primarily  by  the 
compressive  strain  in  the  earth's  crust.  Beds  thus  assume 
folds  known  as  monoclines,  anticlines,  and  synclines. 

A  monocline  is  a  terrace-like  dropping  of  a  bed  without 
changing  the  direction  of  the  dip.  There  is  usually  a  zone, 
more  or  less  shattered,  along  the  folded  portion,  and  such  a 
zone  may  become  a  storage  receptacle.  Monoclines  of  a  gentle 
character  in  Ohio,  which  have  been  detected  by  Orton  in  stud- 
ies of  natural  gas,  have  been  called  **arrested  anticlines."  An 
anticline  is  a  convex  fold  with  opposing  dips  on  its  sides, 
while  a  syncline  is  a  concave  fold  with  the  dips  on  its  sides 
coming  together.    We  speak  of  the  axis  of  a  fold,  and  this 


12  KEMP'S  ORE  DEPOSITS, 

marks  the  general  direction  of  the  crest  or  trough.  The  axis 
is  seldom  straight  for  any  great  distance.  Folds  are  often 
broken  and  faulted  across  the  strike  of  their  axes,  and  this 
causes  what  is  called  a  ** pitch"  of  the  axes  and  makes  the 
original  dips  run  diagonally  down  on  the  final  one.  Folds  are 
the  primary  cause  of  the  phenomena  of  dip  and  strike.  Hori- 
zontal beds  have  neither.  A  dome-like  elevation  of  the  beds, 
with  dips  radiating  in  every  direction  from  its  summit,  is 
called  a  quaquaversal,  but  it  is  a  rare  thing.  An  anticline  or 
syncline  with  equal  dips  on  opposite  sides  of  its  axis  is  called 
a  normal  fold.  If  the  dip  is  steeper  on  one  side  than  on  the 
other,  it  is  an  overthrown  fold ;  if  the  sides  are  crushed  to- 
gether, it  is  a  collapsed,  or  sigmoid  fold. 

Igneous  rocks  are  in  the  form  of  sheets  (the  term  **bed" 
should  be  restricted  to  sedimentary  rocks),  knobs  or  bosses, 
necks,  laccolites,  and  dikes.  A  sheet  is  the  form  naturally  as- 
sumed by  surface-  flows,  and  by  an  igneous  mass  which  has 
been  intruded  between  beds.  It  has  relatively  great  length 
and  breadth  as  compared  with  its  thickness,  and  coincides 
with  its  walls  in  dip  and  strike.  A  knob,  or  boss,  is  an  irregu- 
lar mass,  of  approximately  equal  length  and  breadth,  which 
may  be  related  in  any  way  to  the  position  of  its  walls.  Such 
masses  are  often  left  projecting  by  erosion.  A  neck  is  the  filled 
conduit  of  a  volcano,  which  sometimes  remains  after  the  over- 
lying material  has  been  denuded.  A  laccolite  is  a  lenticular 
sheet  which  has  spread  between  beds  laterally  from  its  conduit, 
and  thus  has  never  reached  the  surface,  unless  revealed  by  sub- 
sequent erosion.  A  dike  is  a  relatively  long  and  narrow  body 
of  igneous  rock  which  has  been  intruded  in  a  fissure.  It  is 
analogous  to  a  vein,  but  the  term  "vein"  ought  not  to  be  ap- 
plied to  an  undoubtedly  igneous  rock.  Some  granitic  mixtures, 
however,  of  quartz,  feldspar,  and  mica,  leave  us  yet  in  uncer- 
tainty as  to  whether  they  are  dikes  or  veins.  (See  Example  51.) 
From  the  above  it  will  be  seen  at  once  that  bosses,  knobs,  and 
necks  may  be  practically  indistinguishable. 


CHAPTER  IL 

THE  FORMATION  OF  CAVITIES  IN   ROCKS  AND    THEIR  SECOND- 
ARY  MODIFICATION — SUBTERRANEAN   WATERS. 

1.02.01.  Tension  Joints. — In  the  contraction  caused  by  cool- 
ing, drying,  or  hardening,  both  igneous  and  sedimentary  rocks 
break  into  more  or  less  regular  masses  along  division  planes, 
called  joints,  or  diaclases.  Numerous  cracks  and  small  cavities 
result.  Basaltic  columns,  or  the  prismatic  masses,  formed  by 
the  separation,  in  cooling  and  consolidating,  of  the  heavier 
basic  rocks,  along  planes  normal  to  the  cooling  surface,  are 
good  illustrations  of  the  first.  Larger  manifestations  of  them 
often  become  filled  with  zeolites,  calcite,  and  other  secondary 


Fig.  1. — Illustration  of  rifting  in  granite  at  Cape  Ann,  Mass. 
After  R.  S.  Tarr.     Amer.  Jour,  of  Sci.,  April,  1891. 

minerals.  Granitic  rocks  and  porphyries  break  up  less  regu- 
larly from  the  same  cause,  but  still  exhibit  prismoids  and 
polygonal  blocks  and  benches.^  Large  cracks  have  been  re- 
ferred to  this  cause,  which  have  afterward  formed  important 
receptacles  for  ores.     (See  Example  11a.) 

The  nature  of  the  strain  which  produces  the  Assuring  makes 

*  J.  P.  Iddings' paper  on  "The  Columnar  Structure  in  the  Igneous  Rocks 
on  Orange  Mountain,  N.  J.,"  Amer.  Jour.  Sci.,  III.,  xxxi.  320,  is  an  excel- 
lent discussion. 


14  KEMP'S  ORE  DEPOSITS. 

the  term  *' tension  joint'' an  excellent  name  for  them. ^  There 
are,  however,  other  varieties  of  tension  joints.  Sedimentary 
rocks,  that  contain  a  large  quantity  of  water  when  first  formed, 
may  lose  it  in  whole  or  in  part,  and  may  shrink  and  crack  for 
this  reason,  precisely  as  does  the  mud  on  the  bottom  of  a  dried 
puddle.  Ledges  in  many  parts  of  the  world  are  exposed  during 
the  day  to  a  hot  sun,  and  during  the  night  cool  down  to  a  com- 
paratively low  temperature.  The  alternate  expansion  and  con- 
traction may  produce  tensional  stresses  leading  to  the  produc- 
tion of  joints.  The  concentric  surfaces  of  parting  which  are 
so  often  displayed  in  granite  quarries,  and  which  resemble  the 
coats  of  an  onion,  have  been  referred  to  this  cause.  When 
stratified  rocks  become  folded  into  anticlines  and  synclines, 
tensional  strains  are  developed  in  the  upper  laj'ers  of  the  anti- 
cline, and  the  lower  layers  of  the  syncline,  respectively  above 
and  below  the  surface  of  no  strain.  Rupture  almost  always 
results,  and  cracks  or  joints  are  produced,  which  nm  parallel 
with  the  axis  of  the  fold.  Cross-folding  may  then  develop  an- 
other series  at  an  angle  with  the  first. 

1.02.02.  Cleavage,  Fissility  and  Compression  Joints. — In 
speaking  of  the  effects  of  pressure  upon  rocks,  it  is  in  many 
respects  convenient  to  follow  again  the  nomenclature  of  Van 
Hise,  as  established  in  the  paper  last  cited, ^  and  to  distinguish 
at  the  outset  between  cleavage  and  fissility.  Cleavage  is  the 
**capacity  present  in  some  rocks  to  break  in  some  directions 
more  easily  than  in  others;"  whereas  fissility  is  *'a  structure  in 
rocks  by  virtue  of  which  they  are  already  separated  into  paral- 
lel laminae  in  a  state  of  nature."  Fissility  is  therefore  practi- 
cally a  development  of  joints  on  a  very  extensive  and  closely 
set  scale,  and  chiefly  in  one  direction.  Cleavage,  on  the  other 
hand,  does  not  necessarily  imply  cavities  and  has  not  a  very 
important  bearing  on  the  present  discussion.  A  case  has  been 
met  in  the  granites  of  Cape  Ann,  however,  that  deserves  men- 
tion. The  granites  are  known  to  possess  a  tendency  to  split 
along  certain  planes  that  greatly  facilitates  the  operations  of 
the  workmen.     R.  S.  Tarr  discovered   by  microscopic  study, 

*  C.  R.  Van  Hise,  "Principles  of  North  American  Pre-Cambrian  Geol- 
ogy," XVI  Annual  Report  Director  U.  S.  Geological  Survey,  Part  I., 
p.  668. 

2  Op.  dt,  p.  633. 


ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS.  15 

that  coincident  with  this  * 'rifting"  there  was  a  minute  breccia- 
tion  that  had  no  connection  with  the  cleavage  of  the  component 
minerals  or  their  bounding  surfaces.  The  brecciation  has 
manifestly  resulted  from  compression,  and  it  is  obvious  that  its 
presence  made  the  granite  much  more  permeable  to  water.  A 
rock  of  this  character,  if  in  a  region  of  ore  deposition,  would 
quite  readily  become  Impregnated. 

Both  the  joints  produced  by  cooling  and  those  formed 
by  drying  and  consolidation  may  be  afterward  modified 
or  increased  by  rock  movements,  and  still  different  ones  may 
be  brought  about  independently  of  either.  Indeed,  it  is  a 
growing  belief  among  observers,  that  even  the  joints  in-  sedi- 
mentary strata,  which  have  been  usually  referred  to  contrac- 
tional  strains  during  consolidation,  are  the  products  of  pressure 
or  of  other  dynamical  causes,  external  to  the  rock  mass  itself. 
It  may  be  a  very  difficult  matter  to  differentiate  the  effect  of 
one  from  that  of  the  other,  but  pressure  and  torsion  would 
naturally  occasion  displacement,  if  only  on  a  microscopic  scale. 
W.  O.  Crosby  has  suggested  the  undulatory  tremor  of  an 
earthquake  as  of  possible  importance.  The  experiments  of 
Daubree  indicated  that  pressure  would  produce  joints,  and  that 
in  a  homogeneous  medium  two  sets  would  result  at  right  an- 
gles with  each  other,  and  each  at  45°  with  the  direction  of  the 
pressure.  This  theoretical  regularity  is  not  met  in  nature, 
alike  from  the  heterogeneous  character  of  rocks  and  from  the 
complexity  of  the  strains  to  which  they  are  subject.  G.  F. 
Becker  has  sought  in  the  several  recent  papers  cited  below  to 
analyze  in  a  mathematical  way  the  theoretical  application  and 
effects  of  such  strains.  Torsional  stresses  referred  to  above 
have  been  suggested  as  having  important  bearings  on  natural 
phenomena,  and  especially  since  the  experimental  work  of 
Daubree  along  these  lines,  but  Becker  is  led  to  question  their 
extended  application  to  rocks. 

As  regards  the  finer  textural  characteristics  of  certain 
joint  surfaces,  J.  B.  Woodworth  has  contributed  some  very 
interesting  observations,  which,  it  is  to  be  hoped,  will  be  ex- 
tended to  a  wide  series  of  rocks.  In  certain  slaty  rocks  near 
Boston,  the  joint  surfaces  for  a  limited  area  exhibited  small 
undulations,  which  diverge  from  a  central  axis,  like  the 
branches  of  a  feather,  but  which  then  bend  in  curved  surfaces 


16  KEMP'S  ORE  DEPOSITS. 

of  much  larger  development,  so  as  to  form  somewhat  extended 
corrugations.  The  author  remarks  the  resemblance  which 
the  distribution  of  certain  great  fractures  in  the  earth's  crust 
bears  to  these  hand  specimens,  a  suggestion  that  might  be  tested 
in  fractured  areas  containing  veins. 

It  is  manifest  that  the  passage  from  joints,  properly  speaking, 
and  as  outlined  above,  to  slaty  cleavage,  schistosity  and  dy- 
namic effects,  that  are  the  results  of  many  small  fractures  and 
shearing  surfaces,  is  a  gradual  one,  and  that  the  two  are  inti- 
mately connected.  The  references  below,  therefore,  embrace 
both,  although  schistosity  is  but  briefly  referred  to  here,  as  its 
connection  is  not  particularly  close  with  the  origin  of  ore 
bodies,  however  much  it  may  afterward  affect  them.^ 

1.02.03.  Cavities  Formed  by  More  Extensive  Movements 
in  the  Earth* s  Crust, — The  strains  produced  by  compression 
in  the  outer  portion  of  the  earth  are  by  far  the  most  important 
causes  of  fractures.  The  compression  develops  a  tangential 
stress  which  is  resisted  by  the  archlike  disposition  of  the  crust. 
(By  the  term  "crust"  is  simply  meant  the  outer  portion  of  the 

1  G.  F.  Becker  on  the  production  of  fissures.  See  paper  on  "The  Struc- 
ture of  a  Portion  of  the  Sierra  Nevada  of  California,"  Bulletin  Geological 
Society  of  America,  II.  49, 1891;  also  "Finite  Homogenous  Strain,  Flow 
andEupture  of  Rocks,"  Idem.,  IV.  13,  1893;  "The  Finite  Elastic  Stress- 
strain  Function,"  Amer.  Jour.  Sci.,  Nov.,  1893,  p.  337.  The  above  are 
rather  mathematical  for  the  general  reader  and  the  following  are  less  so. 
" The  Torsional  Theory  of  Joints,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXIV. 
130,  1894;  "Schistosity  and  Slaty  Cleavage,"  Journal  of  Geology,  IV.  429, 
1896;  "  Reconnoissance  of  the  Gold  Fields  of  the  Southern  Appalachians," 
XVI  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey,  Part  III.,  265-272;  W.  C. 
Crosby,  "Absence  of  the  Joint  Structure  at  Great  Depths,"  Geol.  Maga- 
zine, Sept.,  1881,  p.  416;  "Classification  and  Origin  of  Joint  Structures," 
Proc.  Boston  Soc.  Nat.  Hist.,  XXII.  72,  1882;  "On  the  Joint  Stmcture  of 
Rocks,"  Technology  Quarterly,  1890;  "The  Origin  of  Parallel  and  Inter- 
secting Joints,  Idem. ,  VI.  230,  1898 ;  also  in  Amer.  Geologist,  Dec. ,  1893, 
368;  G.  K.  Gilbert,  "On  the  Origin  of  Jointed  Sti-ucture,"  Amer.  Jour. 
Sci.,  July,  1882,  50;  J.  Le  Conte,  "  Origin  of  Jointed  Structure  in  Undis- 
turbed Clay  and  Marl  Deposits,"  Amer.  Jour.  Sci.,  III.,  xxiii.  238;  W.  J 
McGee,  "  On  Jointed  Structure, "  Amer.  Jour.  Sci.,  III.  xxv.  152,  476. 

An  excellent  bibliography  on  slaty  cleavage  up  to  1885  will  be  found  in  a 
paper  by  Alfred  Harker,  in  Rep.  British  Assoc,  for  the  Advancement  of 
Science,  1885,  813,  and  upon  this  and  other  kindred  subjects,  Daubree's 
Etudes  Synthetiques  de  Geologie  Experimentale,  1879,  Part  I. ;  Sub  Part 
II.,  Chaps.  I. -IV. 


'  ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS.  17 

globe  without  reference  to  the  character  of  the  interior. )  Where 
there  is  insufficient  support,  gravity  causes  a  sagging  of  the 
material  into  synclinals,  which  leave  salient  anticiinals  be- 
tween them.  "Where  the  tangential  strain  is  also  greater  than 
the  ability  of  the  rocks  to  resist,  they  are  upset  and  crumpled 
into  folds  from  the  thrust.  Both  kinds  of  folds  are  fruitful 
causes  of  fissures,  cracks,  and  general  shattering,  and  every  slip 
from  yielding  sends  its  oscillations  abroad,  which  cause  breaks 
along  all  lines  of  weakness.  The  simplest  result,  either  from 
sagging  or  from  thrust,  is  a  fissure,  on  one  of  whose  sides  the 
wall  has  dropped,  or  on  the  other  of  which  it  has  risen,  or  both, 
as  will  be  more  fully  described  under  "Faults."  If  the  rocks 
are  firm  and  quite  thicklj^  bedded,  as  is  the  case  with  lime- 
stones and  quartzites,  the  separation  is  cleanly  cut ;  but  if  they 
are  softer  and  more  yielding,  they  are  sheared  downward  on 
the  stationary  or  lifting  side,  and  upward  on  the  one  which 
relatively  sinks.  Such  fissures  may  pass  into  folds  along 
their  strike,  as  at  Leadville,  Colo. 

1.02.04.  A  phenomenon  which  is  especially  well  recognized 
in  metamorphic  regions,  and  which  is  analogous  to  those  last 
cited,  is  furnished  by  the  so-called  '* shear  zones."  A  faulting 
movement,  or  a  crush,  may  be  made  apparent  in  rocks  of  this 
character  by  changes  in  mineralogical  composition  and  structure, 
as  well  as  by  clearly  fractured  rocks.  Massive  diabases,  for  in- 
st-ance,  pass  into  hornblende  schists  or  amphibolites  for  limited 
stretches.  Garnets  and  other  characteristically  metamorphic 
minerals  appear,  and  pyroxenes  alter  to  amphiboles.  Strains 
are  manifested  in  the  optical  behavior  of  the  minerals  in  thin 
sections  of  specimens  taken  from  such  localities.  These 
crushed  strips,  or  shear  zones,  may  be  formed  with  very  slight 
displacement,  but  they  afford  favorable  surroundings  for  the 
formation  of  ore  bodies.  This  conception  of  the  original  condi- 
tion of  a  line  of  ore  deposition  is  a  growing  favorite  with 
recent  writers,  and  combined  with  the  idea  of  replacement  is 
often  applicable.  Fahlbands,  which  are  very  puzzling  prob- 
lems, may  have  originated  as  shear  zones. 

1.02.05.  A  more  extended  effect  is  produced  by  the  mono- 
cline, which  has  a  double  line  of  shattered  rock  marking  both 
the  crest  and  foot  of  its  terrace.  Anticlines  and  synclines 
occasion    the  greatest    disturbances.     Comparatively     brittle 


18  KEMP'S  OBE  DEPOSITS. 

materials  like  rocks  cannot  endure  bending  without  suffering 
extended  fractures.  When  strained  beyond  their  limit  of  resist- 
ance, along  the  crest  of  an  anticline,  and  in  the  trough  of  a  syn- 
cline,  cracks  and  fractures  are  formed  which  radiate  from  the 
axis  of  each  fold.  As  these  open  upward  and  outward  in  anti- 
clines, they  become  the  easiest  points  of  attack  for  erosion,  so 
that  it  is  a  very  common  thing  to  find  a  stream  flowing  in  a 
gorge,  which  marks  the  crest  of  an  anticline,  while  synclinal 
basins  are  frequently  left  to  form  the  summits  of  ridges,  as  is 
so  markedly  the  case  in  the  semi-bituminous  coal  basins  of 
Pennsylvania.  It  is  quite  probable,  however,  that  the  anti- 
cline may  have  been  leveled  off  at  this  fissured  crest  because  it 
was  upheaved  under  water  and  became  exposed  at  its  vulner- 
able summit  to  wave  action. 

Ore  deposits  may  collect  in  these  fissured  strips,  of  which  the 
lead  and  zinc  mines  of  the  upper  Mississippi  Valley  (Example 
24)  are  illustrations.  Such  fissures  are  peculiar  in  that  they 
exhibit  no  displacement.  The  accompanying  figure  is  from  a 
photograph  of  a  gaping  crack  in  the  Aubrey  (Upper  Carbonif- 
erous) limestone,  twenty-five  miles  north  of  Canon  Diablo  sta- 
tion, Ariz.,  on  the  Atlantic  and  Pa<^ific  Railroad.  It  was 
caused  by  a  low  anticlinal  roll  and  contained  water  about  one 
hundred  feet  below  the  top.  Its  reproductions  of  the  condi- 
tions of  a  vein,  with  horse,  pinches  and  swells,  devious  course, 
and  all,  is  striking.  The  photograph  was  made  by  Mr.  G.  K. 
Gilbert,  of  the  United  States  Geological  Survey,  and  to  his 
courtesy  its  use  is  due. 

While  it  is  true  that  in  many  regions  the  folds  and  fractures 
have  resulted  in  this  simple  way,  and  exhibit  tbe  unmistaka- 
ble course  through  which  they  have  passed,  yet  geological 
structure  is  by  no  means  always  so  clear.  Extended  disturb- 
ances, great  faults  and  displacements,  combined  with  folds 
and  the  intrusion  of  igneous  rocks,  have  often  so  broken  up  a  dis- 
trict that  it  is  a  matter  of  much  difficulty  to  trace  out  the 
course  through  which  it  has  passed.  Subsequent  erosion,  or 
the  superposition  of  heavy  beds  of  gravel  or  forest  growths, 
etc.,  may  so  obstruct  observation  even  of  the  facts  as  to  add  to* 
the  obscurity.  The  expense  of  making  and  the  consequent 
scarcity  of  accurate  contour  maps  to  assist  in  such  work  are 
other  obstacles.     The  profound  dynamic  effects  wrought  by 


ON  THE  FORMATION  OF  CAVITIES  IN  BOCKS.  19 

mountain-making  processes,  although  in  individual  cases  pro- 
ducing only  the  simpler  phenomena  already  cited,  yet  in  gen- 
eral are  much  more  extensive,  and  must  be  considered  in  the 
study  of  many  large  districts.  When  folds  are  the  result  of 
compression  or  thrust,  the  dynamic  effects  are  more  marked 
than  in  those  formed  by  sagging.  Faults  are  larger  and  more 
abundant.  When  sedimentary  beds  have  been  laid  down 
along  an  older  axis  of  granite  or  some  equally  resistant  rock 
and  the  thrust  crowds  the  beds  against  this  axis,  the  conditions 
are  eminently  favorable  to  great  fracturing  and  disturbance. 
The  flanks  of  the  Rocky  Mountains  furnish  such  examples. 

1.02.06.  There  are  also  great  lines  of  weakness  in  the  outer 
portion  of  the  earth,  which  seem  to  have  been  the  scene  of 
faulting  movements  from  a  very  early  period.  Thus,  on  the 
western  front  of  the  Wasatch  Mountains,  in  Utah,  is  a  great 
line  of  weakness,  that  was  first  faulted,  asnearlj^as  we  can  dis- 
cover, in  Archean  times,  and  has  suffered  disturbances  even 
down  to  the  present.  A  few  instances  of  actual  movements 
within  recent  years  have  been  recorded.  In  1889  a  sudden 
small  fold  and  fissure  developed  under  a  paper  mill  near  Ap- 
pleton.  Wis.,  and  heaved  the  building  four  and  a  half  inches. 
(See  F.  Cramer,  "Recent  Rock  Flexure,"  Amer.  Jour.  Sci., 
III.,  xxxix.  220.)  This  occurred  in  what  was  regarded  a  set- 
tled region,  and  one  not  liable  to  disturbance. 

1.02.07.  Wherever  igneous  rocks  form  relatively  large  por- 
tions of  the  globe  they  necessarily  share  extensively  in  ter- 
restrial disturbances.  Not  being  often  in  sufficiently  thin 
sheets,  they  rarely  furnish  the  phenomena  of  dip  and  strike. 
Folds  are  largely  wanting.  Thej^  are  replaced  by  faults  and 
shattering.  The  fissures  thus  formed  are  at  times  of  great  size 
and  indicate  important  movements.  The  Comstock  Lode  fis- 
sure is  four  miles  long  and  in  the  central  part  exhibits  a 
vertical  displacement  of  three  thousand  feet.  (See  2.11.21.) 
Such  fissures  seldom  occur  alone,  but  minor  ones  are  found  on 
each  side  and  parallel  with  the  main  one. 

1.02.08.  The  intrusion  of  igneous  dikes  may  start  earth- 
quake vibrations  which  fracture  the  firm  rock  masses.  Fis- 
sures caused  in  this  way  radiate  from  the  center  of  disturbance 
or  else  appear  in  concentric  rings.  The  violent  shakings  which 
so  often  attend  great  volcanic  eruptions,   and  the  sinking  of 


20 


KEMP'S  ORE  DEPOSITS. 


the  surface  from  the  removal  of  underlying  molten  material, 
all  tend  to  form  cracks  and  cavities.  They  are  possible  causes 
which  may  well  be  borne  in  mind  in  the  study  of  an  igneous 
district. 

1.02.09.  Faults. — When  fractures  have  been  formed  by 
any  of  the  means  referred  to  above,  and  the  opposite  w^alls  slip 
past  each  other,  so  as  not  to  correspond  exactly  at  all  horizons, 
they  are  called  "faults,"  a  term  which  indicates  this  lack  of 
correspondence. 

The  separation  is  chiefly  due  to  the  relative  slipping  down 
or  sinking  of  one  side.  The  distance  through  which  this  has 
taken  place  is  called  the  amount  of  displacement,  or  throw. 


Fig.  3. — Normal  fault,  Leadville,  Colo.    After  A.  A.  Blow. 
Trans.  Amer.  Inst  Min.  Eng.,  XVIII,  180.     Plate  IV. 

Faults  are  most  commonly  inclined  to  the  horizon,  so  that 
there  is  both  a  vertical  and  a  horizontal  displacement.  The  in- 
clination of  a  fault  plane  to  the  horizontal  is  called  the  dip, 
just  as  in  the  case  of  stratified  rocks.  Its  inclination  to  the 
vertical  is  the  hade.  Faults  most  commonly  run  parallel  with 
the  strike  of  inclined  rocks,  and  are  then  called  *' strike-faults.'* 
When  they  cut  across  the  strike  and  are  in  the  direction  of  the 
dip  they  are  called '* dip- faults."     Experience  has  shown  that 


Fia.  2. — Open  fissure  in  the  Aubrey  limestone  (Upper  Carboniferous) 
miles  north  of  Canon  Diablo  Station,  Ariz.,  on  the  A.  &  P.  R.  R. 
Reproduced  from  a  photograph  by  G.  K.  Gilbert,  1892. 
(Science,  August  2.  1895,  118.) 


ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS. 


21 


where  beds  or  veins  encounter  faults  and  operations  are  brought 
to  a  standstill,  the  continuation  is  usually  found  as  follows, 
according  to  Schmidt's  law.  If  the  fault  dips  or  hades  away 
from  the  workings,  the  continuation  is  down  the  hade;  if  it 
dips  toward  the  workings,  it  should  be  followed  upward.  Such 
a  fault  is  called  a  normal,  or  gravity  fault,  and  is  illustrated  in 
the  figure  on  p.  20,  after  A.  A  Blow.  This  is  a  natural  result 
of  the  drawing  apart  of  the  two  sides.  The  least  supported 
mass  would  slip  down  on  the  one  which  has  the  larger  base. 
Less  commonly  the  opposite  movement  results.  Thus,  when 
the  fault  is  due  to  compression,  the  beds  pass  each  other  in  the 
reverse  direction,  and  what  is  called  a  reverse  fault  results. 
The  accompanying  cut  illustrates  a  very  extended  one  in  the 


SECT/ON  f. 


Cohuttu^  ContjlomevaU 

^^^      Ocoee  Slate 

Knox  Dolomite 


^^^^^^^^I^^Z^rzI^^^^^^-^y^  Coimasauga  SfialeS 


StCTlON  S 


Fig.  4.    Reversed  Fault  at  Holly  Creek,  near  Dalton,    Qa.      After  C.  W, 
Hayes,  Bull  G.  S.  A.,  Vol.  II.,  PI  3,  p.  152 


southern  Appalachians.  While  we  would  naturally  think  of  a 
reversed  fault  as  resulting  from  a  compressive  strain,  in  that  in 
this  case  the  lower  wedge-shaped  portion  would  be  forced 
under  the  upper  one,  yet  normal  faults  can  likewise,  in  in- 
stances, be  explained  by  compression.  If  we  consider  the  fault 
to  be  caused  by  the  vertical  thrust  or  component,  that  would  al- 
ways be  present  in  the  compression  of  a  completely  supported 
arch,  this  would  tend  to  heave  upward  the  portion  next  the 
fissure  that  had  the  larger  base.  Along  an  inclined  fracture 
such  portion  is  manifestly  the  under  one.  Again,  if  the  com- 
pressive strain  is  applied  in  a  direction  parallel  w^ith  the 
fissure,  and  not  at  right  angles  to  it,  the  hanging  wall  might 
be  forced  to  bulge  downward  and  the  footwall  upward,  thus 


22  KEMP'S  ORE  DEPOSITS. 

yielding  a  normal  fault  by  compression.  It  is  important  to 
note  whether  the  fault  plane,  both  in  normal  and  in  reversed 
faults,  cuts  inclined  beds  in  the  direction  of  the  dip  or  across 
it,  because  the  relative  amount  of  vertical  and  lateral  displace- 
ment is  much  affected  by  these  considerations.  (See  Margerie 
and  Heim,  Dislokation  der  Erdrinde,  Zurich,  1888.) 

1.02.10.  The  movement  of  the  vv^alls  on  each  other  produces 
grooves  and  polished  surfaces  called  slickensides,  or  slips. 
They  are  usually  covered  with  a  layer  of  serpentine,  talc,  or 
some  such  secondary  product.  The  strain  caused  by  the  move- 
ment may  in  rare  instances  leave  the  slips  in  such  a  state  of 
tension  that  when,  from  any  cause,  such  as  excavation,  the 
pressure  is  relieved,  they  will  scale  off  with  a  small  explosion.^ 
Observations  on  the  directions  of  slips  may,  in  cases  of  doubt, 
throw  some  additional  light  on  the  direction  of  the  movement 
which  occasioned  the  fault.  Some  particular  and  recognizable 
bed  or  vein  may  be  crushed  and  dragged  down  by  the  faulting 
movement,  and  afford  the  so-called  *Hrail  of  the  fault,"  which 
will  indicate  the  direction  of  movement  and  direct  the  miner. 
But  the  best  guide  in  stratified  rocks  is  a  knowledge  of  the  suc- 
cession of  the  beds  as  revealed  by  drill  cores  or  excavations. 
Attempts  have  been  made  to  deduce  mathematical  formulas 
for  the  calculation  of  the  amount  of  downthrow  or  upthrow, 
and  when  sufficient  data  are  available,  as  is  often  the  case  in 
coal  seams,  this  may  be  done.  The  methods  depend  on  the 
projection  of  the  planes  in  a  drawing,  on  the  principles  of  ana- 
lytical geometry,  and  on  the  calculation  of  the  displacements  by 
means  of  spherical  trigonometry.^  Prof.  Hans  Hoefer  has 
called  attention  to  the  fact  that  in  faulting  there  is  frequently  a 
greater  displacement  in  one  por*^ion  of  the  fissure  than  in  a 
neighboring  part,  and  even  a  difference  of  hade.  This  causes 
a  twisting,  or  circular  movement  of  one  wall  on  the  other,  and 


1  See  A.  Strahan,  "On  Explosive  Slickensides,"  Geological  Magazine, 
IV.  401,  522. 

2  See  G.  Koehler,  Die  Storungen  der  Gunge,  Flotze  und  Lager,  Leijjzig, 
1886 ;  William  Englemann.  A  translation  by  W.  B.  Phillips,  entitled,  "Ir- 
regularities of  Lodes,  Veins  and  Beds,"  appeared  in  the  Engineering  and 
Mining  Journal,  June  25,  1887,  p.  454,  and  July  2,  1887,  p.  4.  A  very  ex- 
cellent paper,  having  a  quite  complete  bibliography,  is  F.  T.  Freeland's 
"Fault  Rules."  Trans.  Amer.  Inst.  Min.  Eng.,  XXI.  491,  1892. 


OlS"  THE  FOBMATION  OF  CAVITIES  IN  ROCKS.  23 

needs  to  be  allowed  for  in  some  calculations/  In  the  Engineer- 
ing  and  Mining  Journal  for  April  and  May,  1892,  a  quite 
extended  discussion  of  faults  by  several  prominent  American 
mining  engineers  and  geologists  is  given,  apropros  of  the  ques- 
tion raised  by  Mr.  J.  A.  Church  as  to  whether  fissure  veins 
are  more  regular  on  the  dip  or  on  the  strike.  In  a  relatively 
uniform  massive  rock  the  regularity  should  be  greater  on  the 
dip,  but  in  inclined  and  diversified  stratified  rocks  too  many 
variables  enter  to  warrant  any  sweeping  assertions.  In  soft 
rocks  like  shales  the  fissure  may  become  so  split  into  small 
stringers  as  to  be  valueless.  Again,  in  very  firm  rock,  where 
there  is  little   drawing  apart,  the  fissure  may  be  very  tight. 


Fig.  5.  Illustration  of  an  older  vein,  the  Jurribo,  faulted  by  a  later  one, 

(cross-vein)  at  Newman  Hill,  near  Rico,  Colo.      After  T.   A. 

Rickard,  Trans.  Amer.  Inst.  Min.  Eng.,  XXVI.,  951. 

In  the  veins  of  Newman  Hill,  near  Eico,  Colo,  (see  2-09.11), 
the  fissure  is  so  narrow  above  a  certain  statum  as  practically  to 
fail.  Quartzite  is  a  favorable  rock  for  such  effect.  Despite 
all  rules,  faults  are  often  causes  of  great  uncertainty,  annoy- 
ance, and  expensive  exploration. 

1.02.11.  If  a  number  of  faults  succeed  one  another  in  a 
short  distance,  they  are  called  ''step  faults."  An  older  and 
completed  vein  may  also  be  faulted  by  one  formed  and  filled 
later.  In  such  a  case  the  continuous  one  is  the  younger. 
Figure  5  above  will  illustrate  each  case.  At  the  intersection 
of  the  two,  the  later  vein  is  often  richer  than  in  other  parts. 

1.02.12.  If  a  faulted  series  of  rocks  is  afterward  tilted  and 
eroded,  so  as  to  expose  a  horizontal  section  across  the  strike  of 
the  faulting  plane,  an  apparent  horizontal  fault  may  result;  or 

*  Oesterreiches  Zeitschrift  fiir  Berg-und  Hilttemvesen,  Vol.  XXIX.  An 
abstract  in  English  is  given  by  R.  W.  Raymond,  Titans.  Amer.  Inst.  Min. 
Eng.,  X.  456,  1882. 


24  KEMP'S  ORE  DEPOSITS. 

if  the  erosion  succeeds  normal  faulting  and  lays  bare  two  un- 
conformable beds  each  side  of  the  fissure,  a  lack  of  correspond- 
ence in  plan  as  well  as  in  section  may  be  seen.  Faulting  frac- 
tures are  seldom  straight;  on  the  contrary,  they  bend  and  cor- 
rugate. When  the  walls  slip  past  each  other,  they  often  stop 
with  projection  opposite  projection,  and  depression  opposite 
depression.  These  irregularities  cause  pinches  and  swells  in 
the  resulting  cavity,  and  constitute  one  of  the  commonest  phe- 
nomena of  veins.  Fisij^ures  also  gradually  pinch  out  at  their 
extremities,  or  break  up  into  various  ramifications  that  finally 
entirely  cease.  They  may  pass  into  folds,  as  stated  above.  It  is 
not  surprising,  therefore,  that  in  stratified  rocks,  the  largest 
faults,  as  a  matter  of  observation,  are  usually  parallel  w4th  the 
general  strike.  They  cross  the  strike  or  run  in  the  sense  of  the 
dip  much  less  frequently. 

1.02.13.  Zones  of  Possible  Fracture  in  the  Earth's  Crust. 
— In  a  discussion  of  the  deformation  of  rocks  C.  R.  Van  Hise^ 
has  recently  established  the  conception  of  three  zones  in  the 
earth's  crust,  which  are  intimately  connected  in  a  large  way 
with  the  subjects  just  discussed.  They  are  (1)  an  upper  zone 
of  fracture;  (2)  a  middle  zone  of  combined  fracture  and  plas- 
ticity; (3)  a  lower  zone  of  plasticity.  (1)  Rocks  under  less 
weight  than  their  ultimate  strength,  when  rapidly  deformed, 
are  in  the  zone  of  fracture.  This  is  manifestly  incontroverti- 
ble and  the  conception  adds  to  the  points  touched  on  in  preced 
ing  paragraphs  the  important  further  one  of  the  load  under 
which  the  rocks  stand  at  the  time  of  experiencing  the  strain. 
As  alreadj"  pointed  out,  the  character  of  the  wall  rock  will 
influence  the  resulting  fissure,  firm  rocks  giving  clean-cut 
fissures,  while  soft  rocks,  such  as  shales,  will  more  readily 
break  along  multitudes  of  small  cracks.  The  amount  of  load  is 
also  important,  for  with  its  increase  even  the  firmest  rock 
could  not  fracture,  as  is  shown  in  describing  the  next  two 
zones.  It  is  also  manifest  that  the  depths  of  the  zones  are  vari- 
able in  different  regions,  on  account  of  local  differences  of 
rocks,  and  that  they  are  not  to  be  too  sharply  viewed  in  a  quan- 
titative way. 

^  Principles  of  North  American  Pre  Cambrian  Geology,  XVI.  Annual 
Rep  Dir  U.  S  Geol.  Survey,  Part  1 ,  589,  1896.  See  also  Journal  of 
Geology,  IV.  195,  312,  449,  593. 


ON  TEE  FORMATION  OF  CAVITIES  IN  ROCKS.  25 

In  round  numbers  the  maximum  depths  at  which  cavities 
can  exist  varies  from  500  meters  (1,625  ft.)  for  soft  shales  to 
10,000  meters  (32,500  ft.)  for  firm  granites.  These  maximum 
depths  introduce  zone  (3),  or  the  zone  of  flowage,  wherein  the  load 
is  so  excessive  that  the  yielding  to  deformation  comes  in  the  wa}' 
of  a  viscous  flow,  or  plastic  yielding,  evidences  of  which  are 
visible  in  many  gneisses.  That  such  a  zone  exists  will  appear 
to  any  one  who  reflects  upon  the  necessary  behavior  and  yield- 
ing of  rocks,  which  are  confined  on  all  sides  and  yet  are  com- 
pressed beyond  their  limits  of  resistance.  The  second  or  inter- 
mediate zone  embraces  the  border  region  between  (1)  and  (3), 
or  the  region  of  combined  fracture  and  flowage. 

These  considerations  have  an  important  bearing  on  the  forma- 
tion of  veins,  because  they  indicate  that  veins  must  be  limited 
to  the  outer  portions  of  the  globe  and  must  have  always  formed 
in  such  surroundings.  The  considerations  as  regards  their 
practical  bearing  are  largely  theoretical,  it  must  be  admitted, 
because  even  moderate  estimates  of  the  depth  of  zone  (1)  soon 
reach  below  the  limit  of  possible  mining,^  but  in  their  broad 
scientific  bearings  they  are  a  valuable  aid  to  the  formation  of 
correct  views  on  the  necessary  place  of  origin  of  veins.  The 
"ewige  Teufe"  of  the  earlier  miners  is  therefore  quite  limited. 

1.02.14.  Secondm^y  Modifications  of  Cavities. — Fractures 
and  cavities  of  all  sorts  speedily  become  lines  of  subterranean 
drainage.  The  dissolving  power  of  water,  and  to  a  much 
smaller  degree  its  eroding  power,  serve  to  modify  the  walls 
very  greatly.  An  enlargement  may  result,  and  what  was  per- 
haps a  small  joint  or  fissure  may  become  a  waterway  of  con- 
siderable size.  This  is  especially  true  in  limestones,  in  which 
great  caverns  (like  tbe  Mammoth  Cave  and  Luray's  Cave)  are 
excavated.  Caves  are,  however,  almost  always  due  to  surface 
water,  and  do  not  extend  below  the  permanent  water  level  un- 
less they  have  been  depressed  after  their  formation.^ 

1.02.15.  The  subterranean  movements  of  water  are  of  prime 
importance  in  connection  with  so  many  aspects  of  the  subject 
of  ore  deposits  that  it  is  necessary  to  have  a  fairly  definite  con- 

*  See  in  this  connection  A.  C.  Lane,  "How  Deep  Can  we  Mine?"  The 
Mineral  Industry,  IV.  767.  10,000  ft.  is  placed  as  a  general  limit,  with 
possibilities  as  far  as  15,000,  but  probably  not  much  beyond. 

'  See  J.  S.  Curtis,  Monograph  VII,  U.  S.  Geol.  Survey,  Chap.  VIII. 


26  KEMP'S  ORE  DEPOSITS. 

caption  of  their  nature  and  causes.  Water  falling  on  the  sur- 
face as  rain  in  part  runs  off  at  once,  in  part  evaporates,  at  least 
before  it  has  gone  far,  and  in  part  sinks  into  the  ground. 
With  the  last  named  we  are  especially  concerned.  World-wide 
experience  long  ago  demonstrated  that  under  all  portions  of 
the  land,  unless  possibly  in  excessively  arid  and  exceptional 
districts,  there  is  a  body  of  almost  stationary  water,  that  main- 
tains a  very  constant  level  and  that  will  fill  a  well  if  one  is 
sunk  sufficiently  deep.  Where  the  rainfall  is  heavy  this  *' per- 
manent water  level"  or  "ground  water"  stands  only  a  short 
distance  below  the  surface,  it  may  be  only  a  few  feet ;  but  in 
regions  of  slight  rainfall,  it  is  correspondingly  depressed.  It 
varies  also,  more  or  less,  with  the  nature  of  the  local  rocks, 
with  the  nearness  or  remoteness  of  low-lying  valleys  and  with 
the  geological  structure.^  The  "ground  water"  that  stands  at 
this  level  is  to  be  distinguished  from  the  actively  circulating 
water  above  it — the  "vadose"  circulation  of  Posepny,^  whose 
recent  treatise  has  served  to  focus  attention  upon  this  phase  of 
the  subject — and  is  not  itself  without  motion,  because  where  it 
is  situated  above  some  more  or  less  remote  and  lower  lying 
outlet  it  passes  toward  it  by  a  slow,  gradual  flow,  or  sinks 
downward,  moves  laterally  and  rises  again  by  a  siphonic  ac- 
tion. Cracks  and  clefts  are  the  chief  lines  of  movement  in 
both  these  circulations,  and  instances  are  known  of  communi- 
cations across  wide  intervals.  Capillary  circulations  are  also 
not  lacking  but  are  of  less  quantitative  moment.  As  solvents  of 
rocks  the  ground-water  circulations  are  not  comparable  with  the 
vadose,  for,  as  already  remarked,  caves,  the  chief  results  of 
such  solution  and  removal,  are  essentially  products  of  the 
latter. 

1.02. 16.  The  ground-water  stands  between  the  motive  power 
of  the  overlying  hydrostatic  column  and  the  further  motive 
power  of  the  underlying  heated  zones  of  the  earth,  to  which 
some  of  the  surface  water  attains,  more  or  less  by  capillary 
movements.     Daubree  has  shown  that  capillary  attraction  is 

1  See,  in  this  connection,  T.  C.  Chamberlin,  "The  Requisite  and  Qualify- 
ing Conditions  of  Artesian  Weils,"  Fifth  Annual  Rep.  Dir.  U.  S.  Geol. 
Survey,  131,  1885. 

^Transactions  Amer.  Inst.  Min.  Eng.,  XXIII.  313,1893.  Reissued  as 
*'  Genesis  of  Ore  Deposits,"  in  which  see  p.  17. 


ON  THE  FORMATION  OF  CAVITIES  IN  BOCKS.  27 

■effective  even  against  steam  pressure/  Cooling  but  still 
heated  intrusions  of  igneous  rocks,  which  may  not  necessarily 
reach  the  surface,  are  doubtless  the  most  serious  of  all  these 
internal  stimulators,  and  furnish  us  with  the  most  reasonable 
cause  for  those  active  circulations,  that  have  led  to  ore-deposi- 
tion in  regions  of  extended  mineral  veins.  They  are  at  once 
localized,  of  relatively  abrupt  development,  and  the}^  bring 
great  stores  of  heat  within  the  conceivable  zones  of  the  ground- 
water's existence.  It  is  also  quite  probable  that  waters  and 
other  fluid  or  vaporous  substances  are  emitted  and  driven  out- 
ward, which  are  not  derived  from  infiltrations  from  the  surface, 
but  which  have  been  involved  in  the  substance  of  igneous  mag- 
mas since  their  derivation  from  the  original  nebula.  All  these 
circulations  from  deep-seated  sources  are  more  likely  to  be 
fillers  than  enlargers  of  cavities  in  the  upper  portions  of  the 
zone  of  fracture. 

It  is  conceivable  that  the  heat  necessarily  developed  in  the 
crushing  and  fracture  of  rocks  on  a  large  scale  may  also  be  an 
important  local  stimulus  and  in  this  way  contribute  in  no  small 
degree  to  the  final  results. 

1.02.17.  The  solvent  action  of  water  is  vastly  augmented  by 
the  carbonic  acid  which  it  gathers  from  the  atmosphere,  and 
this  is  the  chief  cause  of  the  excavations  wrought  by  it  in  lime- 
stones. Pure  cold  water  has  comparatively  small  dissolving 
and  almost  no  eroding  power.  It  has  also  been  advocated  that 
various  acids  which  result  from  the  decay  of  vegetable  matter 
aid  in  such  results.^  This  may  be  true,  but  in  general  carbonic 
acid  is  the  chief  agent.  Iron  in  minerals  falls  an  easy  prey, 
as  does  calcium,  and  both  are  dissolved  out  in  large  amount. 
(See  Example  1.)  When  charged  with  alkaline  carbonates, 
water  has  the  power  to  attack  other  less  soluble  minerals,  such 
as  quartz  and  silicates,  and  by  such  action  the  walls  of  a  cavity 
in  the  crystalline  rocks  may  be  much  affected. 

^  The  most  important  works  bearing  on  this  entire  question  of  under- 
ground waters  are  those  of  Daubree,  viz. : 

"Etudes  Synthetiques  de  Geologie  Experimental e,"  1879. 

"Les  Eaux  Souterraines  aux  Epoques  anciennes,"  1887. 

"Les  Eaux  Souterraines  a  I'Epoque  actuelle,"  1887,  3  vols. 

Suggestive  reading  will  also  be  found  in  C.  R.  Van  Hise,  ' '  Metamorph- 
ism  of  Rocks  and  Rock-flowage,  Bull.  Geol.  Soc.  Amer.,  IX.  269. 

'  A.  A.  Julien,  Amer.  Asso.  Adv.  Sci.,  1879,  p.  311. 


2S  KEMP'S  ORE  DEPOSITS. 

1.02. 18.  As  has  been  set  forth  in  a  previous  paragraph,  waters 
percolating  to  great  depths  in  the  earth,  or  circulating  in  re- 
gions of  igneous  disturbances,  become  highly  heated,  and  this 
too  at  great  pressure.  Under  such  circumstances  the  solvent 
action,  is  very  strongly  increased,  and  all  the  elements  present 
in  the  rock-making  minerals  are  taken  into  solution.  Alka- 
line carbonates  are  formed  in  quantity;  silica  is  easily  dis- 
solved; alkaline  sulphides  result  in  less  amount;  and  even  the 
heaviest  and  least  tractable  metals  enter  into  solution,  either 
in  the  heated  v^aters  themselves,  or  in  the  alkaline  liquors 
formed  by  them.  The  action  on  the  walls  of  cavities  and 
courses  of  drainage  is  thus  profound,  and  accounts  for  the  fre- 
quent decomposed  character  of  the  walls  and  the  general  lack 
of  sharpness  in  their  definition.  The  vast  amount  of  siliceous 
material  deposited  by  hot  springs  and  geysers  is  additional  evi- 
dence of  its  importance.  When  the  uprising  solutions  reach 
the  regions  of  diminished  temperature  and  pressure  they  con- 
tribute their  burden  of  dissolved  minerals  to  veins  and  surface 
accumulations. 

1.02.19.  The  composition  of  mineral  springs  is  of  the  great- 
est interest  in  this  connection, and  is  a  subject  that  has  received 
much  attention  in  recent  years. ^  The  vast  majority  of  those 
recorded  contain  chiefly  silica  and  salts  of  alkalies  and  alkaline 
earths,  of  which  a  few  represent  the  gangue  minerals.  Here 
and  there,  however,  examples  with  metallic  contents  have  been 
detected,  and  in  several  instances  springs  have  been  met  in 
deep  mines  and  the  waters  have  been  analyzed.  Often  the  ore 
deposition,  as  indicated  by  these,  seems  to  have  ceased,  but 
again  either  in  the  waters  themselves  or  in  crusts  formed  by 
them,  metallic  minerals  have  been  detected.  In  the  table  be- 
low the  first  seven  relate  to  American  cases,  the  last  three  to 

^  R.  N.  Brackett,  " Mineral  Waters  of  Arkansas,"  Geological  Survey  of 
Arkansas,  1891,  I. 

Gooch  and  Whitfield,  "Analyses  of  Waters  of  the  Yellowstone  National 
Park,"  Bulletin  4:1,  U.  S.  Geol.  Survey. 

A.  C.  Peale,  "Lists  and  Analyses  of  the  Mineral  Springs  of  the  United 
States,  Bulletin  32,  Idem. 

F.  Posepny,  "Genesis  of  Ore  Deposits,"  pp.  26-48. 

J.  Roth,  "  Allgemeine  und  Chemische  Geologic,"  I.  Chap,  x.,  407. 

P.  Schweitzer,  "The  Mineral  Springs  of  Missouri,"  Mo.  Geol  Survey,* 
m.  1892. 


ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS.  29 

European.     All  the  amounts  are  expressed  in  parts  per  mil- 
lion, i.  e.,  grams  per  1,000  liters. 

1.02.20.  In  analyses  I.  and  II.  metallic  salts  were  not  them- 
selves detected,  but  ammonium  carbonate  was,  and  on  its 
presence,  as  well  as  the  results  of  experiment,  Becker  bases  his 
explanation  of  the  introduction  of  the  cinnabar.  Cinnabar  is 
found  to  be  soluble  in  ammoniacal  liquors  under  pressure  and 
heat,  but  to  precipitate  again  as  the  pressure  and  temperature 
fall.  The  water  from  Steamboat  Springs  did  yield  traces  of 
quicksilver,  but  the  crusts  which  had  been  precipitated  at  the 
surface  of  the  ground  in  past  time  afforded  in  this  order:  sul- 
phides of  arsenic  and  antimony,  ferric  hydrate,  lead  sulphide, 
copper  sulphide,  mercuric  sulphide,  gold  and  silver,  and  traces 
of  zinc,  manganese,  nickel  and  cobalt.^  The  waters  from  the 
Geyser  mine  were  of  exceptional  interest.  When  compared 
with  each  other  it  is  noticeable  that  the  vadose  waters  (IV.) 
have  much  less  metallic  matter  than  the  deep-water  (V.),  and 
that  in  the  latter  the  metals  appear  in  much  the  same  relative 
abundance  as  in  the  ore  (VI.  and  VIL).  In  the  "Genesis  of  Ore 
Deposits,"  from  which  analyses  VIII. ,  IX.  and  X.  have  been 
taken,  Posepny  has  collected  many  more,  and  cites  some  in- 
stances abroad  in  which  the  metals  have  also  been  noted.  An- 
timony, arsenic,  bismuth,  iron,  manganese,  copper,  tin,  cobalt, 
nickel,  lead,  zinc  and  uranium  are  to  be  numbered  among 
them.  So  far  as  the  metals  are  concerned  all  the  analyses  in- 
dicate extremely  dilute  solutions,  and  the  waters  must  have 
required  a  very  long  period  of  time  to  yield  the  ore  bodies. 
The  dissolved  content  of  alkaline  salts  must  have  flowed  away 
on  the  surface  and  have  disappeared. 

I.  Water  from  the  Hermann  shaft  at  Sulphur  Bank,  Califor- 
nia, from  a  quicksilver  mine.  Monograph  XIII.,  U,  S.  Geol. 
Survey,  p.  259.    W.  H.  Melville,  Analyst. 

II.  Parrott  shaft,  same  locality.     Idem. 

III.  Steamboat  Springs,  Nev.     Idem.  p.  349. 

IV.  Calculated  composition  of  the  vadose  water  at  the  500- 
ft.  level  of  the  Geyser  silver  mine,  Silver  Cliff,  Colo.,  in  rhyo- 
lite  tuff.  The  analysis  is  made  up  from  analyses  of  the  water 
and  of  the  sediment  that  settled  from  it,  chiefly  by  precipita- 

^  Monograph  XIIL,  U.  S.  Geol.  Survey,  343. 


30 


KEMP'S  ORE  DEPOSITS. 


I. 

II. 

III. 

IV. 

V. 

SiOj         

37.15 

41.85 

25.90 

24  42 

AIqOs 

0.25 

1.06 

A1..0,,  PoOr 

0.80 

1.50 

1.70 

93.50 

FeCOo •. 

0.98 

0.29 

7  25 

MnCOg 

1.19 

CaCOg 

35.20 
23.40 

50.55 

15.77 

366  03 

CaS04 

CaoPoOfi 

1.37 

caS :!.... ...... ... ......: :.::.. 

Trace 

SrCO. 

3.29 

i^';-;:--:::;;::::::::::::: 

18.90 

5.55 

0.99 

42.85 
4.20 
16.60 

621.84 
19  18 

K&i^*........::::::::;:::::::::: 

47.05 

74.70 

197.35 

361.34 

KBr,  KI 

Trace 

Na^COa        . .     . 

1,946.75 

322.60 

689.05 

1,039.75 

43.14 

111.47 

1,411.75 

38.70 
60.50 

1,489.67 
223.53 

NaoSOi 

NaCl      .......................... 

1,102.70 

NaNOg 

2.1» 

Na2b407 

1,8/8.40 

2,404.35 

313.6a 

390.90 

290. 2:^ 

3.58 

8.66 

1.00 

56.50 

NanSi^Oo 

SaHcfi;;::::;;;::;;::;;;:::;::: 

NaHS 

NAoAsSg 

Na^SbSa 

LLSO4 

LiCl.. 

17.30 

(NH^UCOo 

6.64 

4.55 

262.41 

5.00 

2.82 

0.74 

1,751.31 

7.6 

HoS 

cot 

37.20 

1,418.61 

Orcranic  matter ..•• 

HerS,  nNaoS 

Trace. 

PbCO...... 

Trace. 

Trace. 

0.40 

1.74 

CuCOa 

0.04 

ZnCOa 

0.66 



Gold 

Silver 

Lead 

Zinc 

Copper 

Iron... — 
Manganese 

Lime 

Sulphur 

Silica 

Total.... 


VI. 

VII. 

Trace. 

Trace. 

1.05 

1.27 

23.80 

17.60 

14.00 

11.10 

1.50 

2.30 

2.30 

2.00 

1.20 

0.80 

1.70 

12.60 

9.50 

33.60 

46.90 

91.75 

91.47 

Alk.  Carbonates  — 
Earthy   Carbonates 

Alk.  Sulphates 

Earthy  Sulphates... 

Chlorides 

Silica 

Others 


vm. 


352.00 
55.00 
12.00 


6.00 
51.00 


IX. 


1,150.00 
510.00 
82.00 


1.00 


2,eo 


00 
00 
37.00 
6.00 
.58.00 
72.00 
6.00 


tion  mthecarbo}^  XVII.  Ann.  Rep.  Dir.  U.  S.  Oeol.  Surv., 
Part  II.,  p.  463.      W.  F.  Hillebrand,  Analyst. 

V.  Calculated  composition  of  deep  v^aters,  2,000-ft.  level, 
same  place  and  conditions.     Idem. 

VI.,  VII.  Analyses  of  two  carload  lots  of  ore  from  same 
mine,  made  at  Arkansas  Valley  smelter,  Leadville.  Idem, 
p.  457.    The  gangue  was  chiefly  barite,  calcite  and  chalcedony. 

VIII.  Water  from  the  Einigkeit's  shaft,  Joachimsthal,  Bo- 
hemia, presumably  at  a  depth  of  .533  meters  (1,774  ft.),  as  stated 
on  p.  27  of  citation.  Analysis  on  p.  38, ' '  Genesis  of  Ore  Deposits. ' ' 


ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS.  31 

Analyst,  J.    Seifert.      The  table    of  equivalent  temperatures 
on  p.  37  of  original  is  incorrect. 

IX.  Gottesgeschick  mine,  Schwarzenberg,  Saxony.  Idem. 
Analyst,  R.  Richter. 

X.  "Sprudel"  spring  in  a  colliery  at  Brux,  Bohemia.  Idem. 
Analyst,  J.  Gintl. 

1.02.20*  Magnesia  is  one  of  the  alkaline  earths  readily 
taken  into  solution  by  carbonated  waters,  and  when  such  wa- 
ters again  meet  limestone  the  effect  is  often  very  great,  and 
constitutes  one  of  the  most  important  methods  of  the  formation 
of  cavities.  Solutions  of  magnesium  carbonate,  on  meeting 
calcium  carbonate,  effect  a  partial  exchange  of  the  former  for 
the  latter.  This  leaves  the  rock  a  double  carbonate  of  calcium 
and  magnesium,  which  is  the  composition  of  the  mineral  and 
rock  dolomite.  The  process  is  therefore  called  dolomitization. 
(See  Example  25.)  It  may  bring  about  a  general  shrinkage  of 
eleven  or  twelve  per  cent.  In  any  extended  thickness  of  strata 
this  would  cause  vast  shattering  and  porosity.  As  an  illus- 
tration of  its  residts,  the  following  analysis  of  normal,  un- 
changed Trenton  limestone  of  Ohio,  and  of  well  drillings  from 
the  porous,  gas-bearing,  dolomitized  portions  of  the  same,  are 
given.  They  are  taken  from  a  paper  by  Edward  Orton. 
(Amer.  Manuf.  and  Iron  Worlds  Pittsburg,  Dec.  2,  1887.) 

CaC03.  MgCOa.  Fe203,Al203.  SiO^. 
Unchanged  Trenton  limestone.  .79.30        0.92         7.00         12.00 

..82.36        1.67         0.58         12.34 
Dolomitized       *'  "         .  .53.50      43.50         1.25  1.70 

..51.78  36.80 
1.02.21.  Recent  studies  in  ore  deposits  by  Posepny,  Curtis 
and  Emmons  indicate  also  that  solutions  of  metallic  ores  may 
affect  an  interchange  of  their  contents  with  the  carbonate  of 
calcium  or  magnesium  in  limestones  and  dolomities,  leaving 
an  ore  body  in  place  of  the  rocks.  This  change  is  effected 
molecule  by  molecule,  and  is  spoken  of  as  a  metasomatic  inter- 
change or  replacement.  (See  Example  30.)  By  "metasoma- 
tic" is  meant  an  interchange  of  substance  without,  as  in  pseu- 
domorphs,  an  imitation  of  form.  Alteration  of  the  metallic 
ores  may  follow  and  occasion  cavities  from  shrinkage.  (See 
Example  36,  and  Curtis,  on  Eureka,  Nev.,  Monograph  VIII, 
U.  S.  Geol.  Survey,  Chap.  VIII.) 


CHAPTER  III. 

THE  MINERALS    IMPORTANT    AS    ORES;     THE     GANGUE  MINER- 
ALS,   AND   THE   SOURCES   WHENCE   BOTH   ARE   DERIVED. 

1.03.01.  The  minerals  which  form  the  sources  of  the  metals 
are  almost  without  exception  included  in  the  following  com- 
pounds: the  sulphides  and  tellurides,  the  arsenides  and  antimo- 
nides,  the  oxides  and  oxidized  compounds  such  as  hydrous 
oxides,  carbonates,  sulphates,  phosphates,  and  silicates,  and 
one  or  two  compounds  of  chlorine.  A  few  metals  occur  in 
the  native  state.  All  the  other  mineral  compounds  such  as  a 
chromateor  two,  a  bromide  or  iodide,  etc.,  are  rarities.  It  may 
be  said  that  nine-tenths  of  the  productive  ores  are  sulphides, 
oxides,  hydroxides,  carbonates,  and  native  metals.  The  ores 
of  each  metal  are  subsequently  outlined  before  its  particular 
deposits  are  described. 

1.03.02.  The  most  common  gangue  mineral  is  quartz,  while 
in  less  amount  are  found  calcite,  siderite,  barite,  fluorite,  and 
in  places  feldspar,  pyroxene,  hornblende,  rhodonite,  etc.  The 
silicates  are  chiefly  present  where  the  gangue  is  a  rock  and  the 
ore  is  disseminated  through  it.  All  the  common  rocks  serve  in 
this  capacity  in  one  place  or  another. 

1.03.03.  Source  of  the  Metals. — The  metallic  contents  of 
the  minerals  which  constitute  ores  must  logically  be  referred 
to  a  source,  either  in  the  igneous  rocks,  or  in  the  ocean.  If 
the  nebular  hypothesis  expresses  the  truth — and  it  is  the  best 
formulation  that  we  have — all  rocks,  igueous,  sedimentary, 
and  metamorphic,  must  be  traced  back  to  the  original  nebulao 
This,  in  cooling,  afforded  a  fused  magma,  w^hich  chilled  and 
assumed  a  structure  analogous  to  the  igneous  rocks  with  which 
we  are  familiar.  Igneous  rocks  must  thus  necessarily  be  con- 
sidered to  have  furnished  by  their  erosion  and  degradation  the 
materials  of  the  sedimentary  rocks;  while  igneous  and  sedi= 


THE  MINERALS  IMPORTANT  AS  ORES,  ETC.  33 

mentary  alike  have  afforded  the  substances  whose  alterations 
have  produced  the  metamorphic  rocks.  It  may  also  be  true 
that  eruptive  rocks,  especially  when  basic,  have  been  formed, 
by  the  oxidation  and  combination  with  silica,  of  inner  metallic 
portions  of  the  earth,  for  this  is  one  of  our  most  reasonable 
explanations  of  volcanic  phenomena,  suggested  alike  by  the 
composition  of  basalts,  by  the  high  average  specific  gravity  of 
the  globe,  and  by  analogy  with  meteorites. 

1.03.04.  As  opposed  to  this  conception,  there  are  those  who 
would  derive  the  metallic  elements  of  ores  from  the  ocean,  in 
which  they  have  been  dissolved  from  its  earliest  condensation. 
Thus  it  is  said  that  substantially  all  the  metals  are  in  solution 
in  sea  water.  From  the  sea  they  are  separated  by  organic 
creatures,  it  may  be,  through  sulphurous  precipitation,  attend- 
ant on  the  decay  of  dead  bodies.  The  accumulations  of  the 
remains  of  organisms  bring  the  metals  into  the  sedimen- 
tary strata.  Once  thus  entombed,  circulation  may  concentrate 
them  in  cavities.  When  present  in  igneous  rocks,  the  latter 
are  regarded  as  derived  from  fused  sediments.  If  the  metallic 
contents  of  sedimentary  rocks  do  not  come  from  the  ocean  in 
this  way,  the  igneous  rocks  as  outlined  above  are  the  only  pos- 
sible source.  No  special  mention  is  here  made  of  the  meta- 
morphic rocks,  because  in  their  original  state  they  are  refera- 
ble to  one  or  the  other  of  the  two  remaining  classes.  But  it  is 
not  justifiable  in  the  absence  of  special  proof  to  consider  them 
altered  sediments,  any  more  than  altered  igneous  rocks,  and  it 
is  doubtless  true  that  the  too  generally  and  easily  admitted 
sedimentary  origin  for  our  gneisses  and  schists  has  materially 
hindered  the  advance  of  our  knowledge  of  them  in  the  last 
forty  years. 

1.03.05.  Microscopic  study  of  the  igneous  rocks  has  shown 
that,  with  few  exceptions,  the  rock-making  minerals  separate 
from  a  fused  magma  on  cooling  and  crystallizing,  in  a  quite 
definite  order. ^  Thus  the  first  to  form  are  certain  oxides,  mag- 
netite, specular  hematite,  ilmenite,  rarely  chromite  and  pico- 
tite,  a  few  silicates,  unimportant  in  this  connection  (zircon, 
titanite),  and  the  sulphides  pyrite  and  pyrrhotite.  Next  after 
these  metallic  oxides,  etc.,  the  heavy,  dark-colored,  basic  sili- 

*  H.  Rosenbusch,  "Ueber  das  Wesen  der  koernigen  und  porphyrischen 
Stnictur  bei  Massengesteine,"  Neues  Jahrhuch,  1882,  ii.,  1. 


34  KEMP'S  ORE  DEPOSITS. 

cates,  olivine,  biotite,  augite,  and  hornblende  are  formed.  All 
these  minerals  are  characterized  by  high  percentages  of  iron, 
magnesium,  calcium,  and  aluminum.  They  are  very  gener- 
ally provided  with  inclusions  of  the  first  set.  Following  the 
bisilicates  in  the  order  of  crystallization,  come  the  feldspars, 
and  after  these  the  residual  silica,  which  remains  uncombined, 
separates  as  quartz. 

1.03.06.  If  we  regard  the  igneous  rocks  as  the  source,  the 
metallic  elements  are  thus  to  be  ascribed  to  the  first  and  sec- 
ond series  of  crystallizations,  while  the  elements  of  the  gangue 
minerals  are  derived  from  the  last  three.  It  is  a  doubtful  point 
whether  the  less  common  metals,  such  as  copper,  silver  and 
nickel,  enter  into  the  composition  of  the  dark  silicates  as  bases, 
replacing  the  iron,  alumina,  lime,  etc.,  or  whether  they  are 
present  in  them  purely  as  inclusions  of  the  first  series.  F. 
Sandberger^  argues  in  support  of  the  first  view,  but  his  critics, 
notably  A.  W.  Stelzner,  cast  doubt  upon  his  conclusions  on  the 
ground  that  his  chemical  methods  were  indecisive.  The  case 
is  briefly  this:  Sandberger,  as  an  advocate  of  views  which  will 
be  subsequently  outlined,  separated  the  dark  silicates  of  a  great 
many  rocks.  By  operating  on  quantities  of  thirty  grams  he 
proved  the  presence  in  them  of  lead,  copper,  tin,  antimony, 
arsenic,  nickel,  cobalt,  bismuth,  and  silver,  and  considered 
these  metals  to  act  as  bases.  The  weak  point  of  the  demonstra- 
tion consists  in  dissolving  out  from  the  powdered  silicate  any 
possible  inclusions.  There  seems  to  be  no  available  solvent 
which  will  take  the  inclusions  and  be  without  effect  on  the 
silicates.  This  is  the  point  attacked  by  the  critics,  and  appa- 
*  rently  with  reason.  It  is,  however,  important  to  have  shown 
the  presence  of  these  metals,  even  though  their  exact  relations 
be  thus  doubtful.  Quite  recently  in  a  series  of  "Notes  on  Chil- 
ean Ore  Deposits."  Dr.  Moricke^  mentions  native  gold  in 
pearlstone  (obsidian)  from  Guanaco,  in  skeleton  crystals  in  the 

^  The  principal  paper  of  Professor  Sandberger  is  his  "Untersuchungen 
fiber  Erzgange,"  1882,  abstracted  in  the  Engineering  and  Mining 
Journal,  March  15,  22,  and  29,  1884;  but  a  long  series  of  others  might  be 
cited  in  which  the  investigations,  notably  at  Pribram,  Bohemia,  are  in- 
terpreted as  indicated  above  A.  W.  Stelzner,  B.  and  H.  Zeit. ,  xxxix. ,  No. 
3,  Zeitsch.  d.  d.  a.  G^eseZZ. ,  xxxi.  644.  "Die  Lateral-secretions-Theorie,  etc. " 
Reprint  Freiberg,  1889. 

^  Tschermaks  Min.  and  Petrog.  Mitth. ,  XII. ,  p.  195. 


THE  MINERALS  IMPORTANT  A8  ORES,  ETC.  35 

glass,  as  inclusions  in  perfectly  fresh  plagioclase  and  sanidine 
crystals,  and  in  spherulites.  G.  P.  Merrill  has  recorded  gold 
as  an  original  mineral  in  biotite-granite  from  Sonora,  Mexico.^ 
A.  Simundi  reported  years  ago  the  existence  of  gold  in  the  gran- 
ites of  Owyhee  Co.,  Idaho,  far  from  any  vein,  to  an  amount 
equal  to  25  cents  per  ton.^  The  existence  of  silver  in  quartz- 
porphyry  has  been  demonstrated  in  this  country  by  J.  S.  Curtis, 
at  Eureka,  Nev.  f  both  the  precious  metals  have  been  shown  by 
G.  F.  Becker  to  be  in  the  diabase  near  the  Comstock  Lode;^  and, 
by  the  same  investigator,  antimony,  arsenic,  lead  and  copper, 
were  proved  to  be  contained  in  the  granite  near  Steam- 
boat Springs,  Nov.*  S.  F.  Emmons  has  also  shown  that 
the  porphyries  at  Leadville  contain  appreciable,  though  small, 
amounts  of  silver/  Of  forty-two  specimens  tested,  thirty -two 
afforded  it ;  of  seventeen  tested  for  lead,  fourteen  yielded  results. 
Emmons  has  also  recorded  determinations  of  silver  by  L.  G. 
EakijDs  in  the  eruptive  rocks  of  Custer  Co,,  Colo.,  in  connection 
with  investigations  upon  the  interesting  ore-bodies  of  the  dis- 
trict. Nine  rocks  were  assayed,  embracing  trachytes,  an  ande- 
site-breccia,  a  different  andesite,  rhyolite,  red  granite,  black 
granite,  the  separated  bisilicates  of  the  last-named,  and  diorite. 
Five  out  of  the  nine  contained  appreciable  amounts,  viz.,  one 
trachyte,  the  rhyolite,  the  diorite,  and  both  granites.  The 
amounts  vary  from  0.005  to  0.402  of  an  ounce  per  ton.  The 
separated  bisilicates  yielded  0.045  per  cent,  lead  and  0.04  of  an 
ounce  of  silver.^  Undoubtedly  the  multiplication  of  tests  will 
show  similar  metallic  contents  in  other  regions.  Thus  the 
augite  of  the  eastern  Triassic  diabase  will  pmbably  yield  cop- 
per, for  this  metal  is  abundant  in  connection  with  the  outflows. 
1.03.07.  Among  the  igneous  rocks  certain  metals  seem  to 
be  characteristically  associated  with  some  varieties,  others 
again  with  a  different  series,  while  to  many  no  generalizations 
apply.  The  basic  rocks  are  the  richest  in  iron,  but  the  metal 
is  not  lacking  in  the  most  acidic.     Copper  in  association  with 

^  G.  P.  Merrill,  Gold  in  Granite,  Amer.    Jour.    Sci.,  April  1896,  309,  Si- 
mundi's  results  are  given  by  G.  F.  Becker. — Tenth  Census,  XIII.  52. 
^  Monograph  VIL,  U.S.  Geol.  Survey,  p.  80. 
^  Monograph  III. ,  U.  S.  Geol.  Survey. 
"  Monograph  XIIL,  U.  S.  Geol.  Survey,  p.  350. 
^  Monograph  XII.,  U.  S.  Geol.  Survey,  p.  569. 
*  XVII  Annual  Rep.  Director  U.  S.  Geol.  Survey,  Part  II.,  471. 


36  KEMP'S  ORE  DEPOSITS. 

nickel  and  some  cobalt  is  found  in  widely  separated  parts  of 
the  world  in  basic  gabbros,  but  other  cases  are  equally  pro- 
nounced in  which  it  seems  connected  with  igneous  rocks  of 
medium  acidity,  or  with  sediments  having  no  visible  connec= 
tion  with  igneous  rocks  at  all.  The  greatest  copper  district  now 
productive, Butte, Mont.,  has  only  granites  and  rhyolites  (quartz- 
porphyries)  exposed  for  miles  around.  Lead  and  zinc  are  more 
commonly  associated  with  limestones  than  with  any  other  one 
rock,  but  the  precipitating  action  of  this  rock,  rather  than  any 
original  content  of  the  metals  in  it,  is  probably  responsible  for 
the  association.  In  other  respects  no  generalizations  are  possiblOo 
Gold  and  silver  are  cosmopolitan  in  their  relations.  The 
former  has  been  found  in  the  native  state  in  igneous  granite 
and  perlite,  and  with  pyrrhotite  in  basic  gabbros,  aside  from 
its  occurrence  in  veins.  Silver  in  one  locality  and  another  is 
a  companion  of  almost  all  types  of  rock ;  chromium  and  plati- 
num are  certainly  at  home  in  the  basic  peridotites  and  -their 
serpentinous  alteration  products,  and  tin  is  seldom  seen  except 
in  connection  with  granite.  The  other  lesser  metals  that  are 
of  serious,  practical  importance  admit  of  no  general  statements 
that  are  not  largely  speculative.^  The  rarer  elements  do,  however 
present  some  striking  associations.  The  ''rare  earths"  seldom 
if  ever  occur  in  notable  amount  except  in  pegmatites  and  gran- 
itic rocks.  Vanadium  finds  its  peculiar  home  in  titaniferous  mag- 
netite, but  it  is  of  remarkably  wide  distribution  in  basic  rocks 
in  general,  as  shown  by  over  sixty  analyses  by  Hillebrand  and 
Stokes.^  The  amounts  are  small,  in  only  one  case  reaching  a 
tenth  of  one  per  cent.,  and  the  vanadium  favors  the  dark  sili- 
cates, especially  biotite.  It  has  also  been  detected  in  surpris- 
ing quantities  in  the  ashes  of  coals  in  Argentina  and  Peru.^ 

^  These  questions  have  been  discussed  at  length  by  L.  De  Launay, 
"Contribution  a  I'Etude  des  Gites  Metallif eres, "  Annalesdes  Mines, 'Kil,, 
1897,  119-228. 

J.  H.  L.  Vogt,  "Ueber  die  relative  Verbreitung  der  Elemente,  besonders 
der  Schwermetalle  und  ueber  die  Concentration  des  urspriinglich  fein 
vertheilten  Metallgehaltes  zu  Erzlagerstatten.  Zeitsch.  fur  praktisehe 
Geologie,  August,  1898,  to  January,  1899. 

2  W.  F.  Hillebrand,  "  Distribution  and  Quantitative  Occurrence  of  Vana- 
dium and  Molybdenum  in  Rocks  of  the  United  States,"  Amer.  Jour,  Sci. 
September,  1898,  209. 

'  W.  P.  Blake,  Engineering  and  Mining  Journal,  Aug.  11,  1894,  p.  128. 
Vanadium  has  been  detected  by  R.  S.  McCaffery,  E.  M.,  in  coals  used  at 
Casapalca,  Peru. 


\* 


THE  MINERALS  IMPORTANT  A8  ORES,  ETC.  37 

Molybdenum  is  much  rarer  and  appears  to  be  limited  to  the 
acidic  rocks.  The  mineral  molybdenite  is  seldom  met  except 
in  pegmatites.  Tungsten  has  practically  the  same  associa- 
tions as  tin. 

1.03.08.  That  the  metals  are  so  generally  combined  with 
sulphur  in  ore  deposits  seems  to  be  due  to  the  extended  distri- 
bution of  this  element,  and  to  its  vigorous  precipitating  action 
on  nearly  all  the  metals  at  the  temperatures  and  pressures 
Avhich  prevail  near  the  earth's  surface.  Sulphur  is  widespread 
in  pyrrhotite  and  pyrite,  original  minerals  in  many  igneous 
rocks,  and  ones  much  subject  to  alteration;  while  sulphuretted 
hydrogen  is  common  in  waters  from  sedimentary  rocks,  and  is 
a  very  general  result  of  organic  decomposition.  Natural  gas 
and  petroleum  from  limestrne  receptacles  almost  always  con- 
tain it.^  Many  sulphides,  too,  are  soluble  under  the  pressures 
and  temperatures  prevailing  at  great  depths,  but  are  deposited 
spontaneously  at  the  pressures  and  temperatures  prevailing  at 
or  near  the  surface. 

1.03.09.  Where  veins  occur  in  igneous  rocks  the  bases  for 
gangue  minerals  have  been  obtained  from  the  rock-making 
silicates.  Calcium  is  afforded  by  nearly  all  the  important 
ones ;  silicon  is  everywhere  present ;  barium  has  been  proved  in 
many  feldspars,  in  small  amount;  and  magnesia  is  present  in 
many  pyroxenes  and  amphiboles.  Of  the  sedimentary  rocks, 
limestone  of  course  affords  unlimited  calcium,  and  recently 
Sandberger  reports  that  he  has  identified  microscopic  crystals  of 
barite  in  the  insoluble  residues  of  one.^  This  is  of  interest,  as 
barite  is  such  a  common  gangue  in  limestone. 

1.03.10.  It  may  be  remarked  that  the  natural  formation  of 
both  ore  and  gangue  minerals  has  doubtless  proceeded  in  na- 
ture with  great  slowness,  and  from  very  dilute  solutions.  Both 
classes  exhibit  a  tendency  to  concentrate  in  cavities,  even  from 
a  widely  dispersed  condition  through  great  masses  of  compara- 
tively barren  rock.  The  formation  may  have  proceeded  when 
the  walls  were  far  below  their  present  position  with  regard  to 

^  See,  in  this  connection,  J.  F.Kemp,  "The  Precipitation  of  Metallic 
Sulphides  by  Natural  Gas, ''jEJ^igrmeermg  and  JtfimngrJbi<r?iaZ,  Dec.  13, 1890. 

2  Sitzungsberichte  d.  Math.  phys.  Classe  d.  k.  bayer,  Akad.  d.  Wiss., 
1891,  xxi.  291.  See  also,  W.  F.  Hillebrand,  "The  Widespread  Occurrence 
of  Barium  and  Strontium,  in  Silicate  Rocks.  "—Joztr.  A.mer.  Chem.  Soc, 
February,  1894,  p.  81. 


38  KEMP'B  ORE  DEPOSITS. 

the  surface,  so  that  to  those  inclined  a  wide  latitude  for  specu- 
lation on  origin  is  afforded.  It  is  possible  that  in  the  earlier 
history  of  the  globe  circulations  were  more  active  than  they 
are  now — a  line  of  argument  on  which  a  conservative  writer 
would  hesitate  to  enlarge. 

1.03.11.  In  the  above  discussion  of  the  sources  of  the  ores 
and  gangue,  the  vein-filling  has  been  considered  as  primarily 
derived  from  the  barren  wall  rock  or  from  deep-seated  sources, 
and  as  precipitated  in  its  present  position  in  the  first  concen- 
tration. Yet  in  instances  it  is  by  no  means  improbable  that 
vein-fillings  as  found  to-day  are  the  product  of  several  concen- 
trations, and  that  a  deposit  sufficiently  rich  to  work  may  be 
the  result  of  two,  or  more  migrations  since  the  first  depar- 
ture from  an  originally  sparsely  disseminated  condition  in  the 
mother  rock.  L.  De  Launay  has  elaborated  this  view  in  the 
paper  cited  abcve.^  In  a  later  paragraph  of  this  book,  1.05.06, 
the  secondary  alterations  of  those  portions  of  veins  that  lie  in 
the  region  of  the  vadose  circulation  is  taken  up,  but  M.  De 
Launay  carries  the  idea  much  further  in  suggesting  that  in 
many  veins  the  present  filling  may  be  due  to  the  concentration 
of  ore  from  much  more  of  the  vein  than  now  appears  above 
the  rich  places.  It  is  certainly  true,  that,  if  a  vein  were 
formed  several  geological  periods  back, it  would  have  shared 
in  all  the  elevations  and  depressions  to  which  its  region  had 
been  subjected  and  consequently  to  considerable  changes  in  the 
relations  of  the  ground  water  and  the  vadose  circulations.  An 
explanation  would  also  be  afforded  of  the  richness  of  some 
veins  that  has  been  marked  within  limited  distances  of  the 
surface  and  that  has  decreased  in  depth.  W.  H.  Weed  has 
noted  cases  of  this  character  in  Montana  that  are  not  as  yet 
(1899)  described  in  print. 

^  The  full  title  of  M.  De  Launay's  paper  is:  I.  Sur  1'  importance  des 
gites  d'  inclusion  et  de  segregation  dans  une  classification  des  gites  metal- 
liferes.  II.  Sur  le  role  des  phenomenes  d'alteration  superficielle  et  de 
remise  en  mouvement  dans  la  constitution  de  ces  gisements.  This 
may  be  freely  translated.  I.  On  the  importance  of  magmatic  inclusions 
and  segregations  in  a  classification  of  ore  deposits.  II.  On  the  part 
played  by  phenomena  of  superficial  alteration  and  of  the  renewal  of 
migration  in  the  constitution  of  these  deposits. 


CHAPTER  IV. 

ON  THE  FILLING   OF  MINERAL  VEINS. 

1.04.01.  Bearing  in  mind  what  precedes,  the  preliminaries 
for  the  discussion  of  mineral  veins  are  set  in  order.  We  have 
traced  the  formation  of  cavities  by  the  shrinkage  of  rock  masses 
in  cooling  or  drying,  by  the  movements  and  disturbances  of 
the  earth's  crust  (which  are  far  the  commonest  and  most  im- 
portant causes),  and  by  dolomitization.  The  enlargement  of 
such  cavities  by  subterranean  circulations  followed,  and  the 
general  effect  of  waters,  cold  and  heated.  The  sources  of  the 
elements  of  the  useful  minerals  were  pointed  out  so  far  as 
known.  All  these  general  and  indisputable  truths  assist  in  the 
drawing  of  right  conclusions.  It  should  be  emphasized,  as 
will  appear  later,  that  mineral  veins  or  cavity  fillings  do  not 
embrace  all  metalliferous  deposits.  On  the  contrary,  the  de- 
posits which  either  form  beds  by  themselves,  or  which  are  dis- 
seminated through  beds  of  barren  rock  and  are  of  the  same  age 
with  them,  do  not  enter  into  the  discussion.  They  are  charac- 
terized by  being  younger  than  their  foot  walls,  and  older  than 
the  hanging.  Their  geological  structure  is  far  simpler,  and, 
as  will  appear  in  the  discussion  of  particular  examples,  the 
working  out  of  their  origin  does  not  so  often  carry  the  investi- 
gator into  the  realms  of  speculation  and  hypothesis.  And  yet 
it  is  not  to  be  inferred  from  the  prominence  here  given  to  the 
discussion  of  veins  that  bedded  deposits  yield  to  them,  in  any 
degree,  in  importance.  Iron  ores,  for  instance,  are  often  in 
beds. 

1.04.02.  Methods  of  Filling — Methods  of  filling  were 
summed  up  a  very  long  time  ago  by  Von  Herder  and  Von 
Cotta,^  as  follows:  1.  Contemporaneous  formation.  2.   Lateral 

'  Erzlagerstdtten,  2d  ed.,  1859,  Vol.,  I.,  p.  172.  A  later  tabulation  is 
given  by  G.  F.  Becker  in  Monograph  XIII,  U.  S.  Geological  S:iirvey,  pp. 
444,  445. 


40  KEMP'S  ORE  DEPOSITS. 

secretion.  3.  Descension.  4.  Ascension  b}"  {a)  infiltration, 
or  {h)  sublimation  with  steam,  or  (c)  by  sublimation  as  gas,  or 
(d)  by  igneous  injection.  To  these  should  be  added  the  more 
recent  theory  of  (5)  replacement,  which,  however,  is  rather  a 
method  of  precipitation  than  of  derivation.  No  one  longer  be- 
lieves in  contemporaneous  formation,  and  descension  has  an 
extremely  limited,  if,  indeed,  any  application.  Ascension  by 
sublimation  as  gas  or  with  steam,  or  by  igneous  injection,  has 
very  few  good  applications.  The  discussion  is  practically  re- 
duced to  lateral  secretion  and  to  ascension  by  infiltration. 

1.04.03.  Lateral  Secretion. — By  lateral  secretion  is  under- 
stood the  derivation  of  the  contents  of  a  vein  from  the  wall 
rock.  The  wall  rock  ma}^  vary  in  character  along  the  strike 
and  in  depth.  Three  interpretations  may  be  made,  two  of 
which  approach  a  common  middle  ground  with  ascension  by 
infiltration.  It  may  first  be  supposed  that  the  vein  has  been 
filled  by  the  waters  near  the  surface  which  are  known  to  be 
soaking  through  all  bodies  of  rock,  even  where  no  marked 
waterway  exists,  and  which  seep  from  the  walls  of  any  opening 
that  may  be  afforded.  Being  at  or  within  comparatively  short 
distances  of  the  surface,  the  waters  are  not  especially  heated. 
As  they  emerge  to  the  oxidizing  and  evaporating  influence  of 
the  air  in  the  cavity,  their  burden  of  minerals  is  deposited  as 
layers  on  the  walls.  The  second  interpretation  supposes  the 
walls  to  be  placed  during  the  time  of  the  filling  at  considera- 
ble depths  below  the  surface,  so  that  the  percolating  waters  are 
brought  within  the  regions  of  elevated  temperature  and  pres- 
sure. Essentially  the  same  action  takes  place  as  in  the  first 
case.  The  third  interpretation  increases  the  extent  of  the  rock 
leached.  Thus,  if  a  mass  of  granite  incloses  a  vein  and  ex- 
tends to  vast  depths,  we  may  suppose  the  waters  to  come  from 
considerable  distances,  and  to  derive  their  dissolved  minerals 
from  a  great  amount  of  rock  of  the  same  kind  as  the  walls. 
Portions  of  this  may  even  be  in  the  regions  of  high  tempera- 
ture, while  the  place  of  precipitation  is  nearer  the  surface. 
These  last  two  interpretations  have  much  in  common  with  the 
theory  of  ascension  by  infiltration,  and  on  this  common  middle 
ground  lateral -secretionists  and  infiltration-ascensionists  may 
be  in  harmony. 

1.04.04.  Ascension  by  Infiltration. — The  theory  of  infil- 


I 


ON  THE  FILLING  OF  MINERAL   VEINS.  41 

tration  by  ascension  in  solution  from  below  considers  that  ore- 
bearing  solutions  come  from  the  heated  zones  of  the  earth,  and 
that  they  rise  through  cavities,  and  at  diminished  temperatures 
and  pressures  deposit  their  burdens.  No  restriction  is  placed 
on  the  source  from  which  the  mineral  matter  has  been  derived. 
Indeed,  beyond  the  fact  that  it  is  "below,"  and  yet  within  the 
limits  reached  by  waters,  all  of  which  have  descended  from  the 
surface,  and  that  the  metals  have  been  gathered  up  from  a  dis- 
seminated condition  in  rocks — igneous,  sedimentary  and  meta- 
morphic  —no  more  definite  statement  is  possible.  This  theory 
is  of  necessity  largely  speculative,  because  the  materials  for  its 
verification  are  beyond  actual  investigation. 

1.04.05.  In  favor  of  lateral  secretion  the  following  argu- 
ments may  be  advanced.  I.  According  to  Sandberger,  actual 
experience  with  the  conduits,  either  natural  or  artificial,  of 
mineral  springs,  shows  that  a  deposit  seldom,  if  ever,  gathers 
in  a  moving  current.  It  is  only  when  solutions  come  to  rest 
on  the  surface  and  are  exposed  to  oxidation  and  evaporation 
that  precipitation  ensues.  Deposits  in  veins  have  therefore 
formed  in  standing  waters,  whose  slight  overflow  or  evapora- 
tion would  be  best  compensated  b}^  the  equally  slight  and  grad- 
ual inflow  from  the  walls.  If  in  hot  springs  there  were  a 
strong  and  continuous  flow  from  below,  and  discharge  from 
above,  the  mineral  matter  would  reach  the  surface.^  Hence  the 
deposit  would  be  more  likely  to  gather  by  the  slow  infiltrations 
from  the  wall  rock,  which  would  stand  in  cavities  like  the 
water  of  a  well.  We  have,  however,  some  striking  instances 
of  deposits  in  artificial  conduits. 

Prof.  H.  S.  Munroe  has  called  the  writer's  attention  to  a  case 
met  by  him  in  1891.  The  fourteen-inch  column  pipe  of  a 
pump  at  the  Indian  Kidge  Colliery,  Shenandoah,  Pa.,  which 
was  raising  ferruginous  waters,  became  reduced  in  diameter  to 
five  inches  within  two  years  by  the  deposit  of  limonite.  The 
same  amount  of  water  was  forced  through  the  five-inch  hole  as 
through  the  fourteen-inch.  By  figuring  out  the  stroke  and 
cylinder  contents,  it  was  found  that  in  the  clear  pipe  the  water 
moved  162  feet  per  minute,  and  in  the  contracted  pipe  1,268 
feet.  And  yet  the  deposit  gathered.  The  conditions  necessi- 
tated the  continuous  action  of  the  pump,  and  it  was  not  idle 
1  (sandberger,   Untersuchungen  uber  Erzgdnge,  Heft  I. 


42  KEMPIS  ORE  DEPOSITS. 

over  two  hours  in  each  two  months  of  that  period.  The  boiler 
feed-pipes  of  steamers  plying  on  the  Great  Lakes  also  become 
coated  with  salts  of  lime.  Years  ago  a  disastrous  boiler  ex- 
plosion occurred  from  the  virtual  stoppage  of  the  feed  by  this 
precipitation. 

1.04.06.  II.  If  a  vein  were  opened  up,  in  mining,  which 
ran  through  two  different  kinds  of  rock,  and  if  in  the  one  rock 
one  kind  of  ore  and  gangue  minerals  were  found,  and  in  the 
other  a  different  set,  the  wall  rock  would  clearly  have  some 
influence.  Thus  in  a  mine  at  Schapbach,  in  the  Black  Forest, 
investigated  by  Sandberger,  a  vein  ran  through  granite  and 
gneiss.  The  mica  of  the  granite  contained  arsenic,  copper,  co- 
balt, bismuth  and  silver,  but  no  lead.  The  principal  ore  in 
this  portion  was  tetrahedrite.  The  mica  of  the  gneiss  con- 
tained lead,  copper,  cobalt,  and  bismuth,  and  the  vein  held 
galena,  chalcopyrite,  and  a  rare  mineral,  schapbachite,  contain- 
ing bismuth  and  silver,  but  probably  a  mixture  of  several  sul- 
phides. No  two  ores  were  common  to  both  parts  of  the  vein. 
Another  well-established  foreign  illustration  is  at  Klausen,  in 
the  Austrian  Tyrol.  Lead,  silver,  and  zinc  occurred  in '  the 
veins  where  they  cut  diorite  and  slates,  but  copper  where  mica 
schist  and  felsite  formed  the  walls.  In  America  there  are  a 
number  of  similar  cases.  At  the  famous  Silver  Islet  mine^  on 
Lake  Superior  the  vein  runs  through  unaltered  flags  and 
shales,  and  then  crosses  and  faults  a  large  diorite  dike.  Where 
the  diorite  forms  the  walls,  the  vein  carries  native  silver  and 
sulphides  of  lead,  nickel,  zinc,  etc.,  but  where  the  flags  form 
the  walls  the  vein  contains  only  barren  calcite.  Along  the 
edges  of  the  estuary  Triassic  sandstones  of  the  Atlantic  bordei, 
where  they  adjoin  Archean  gneiss,  a  number  of  veins  are 
found  which  yield  lead  minerals,  while  in  the  sandstones  near 
the  well-known  diabase  sheets  and  dikes  are  others  carrying 
copper  ores.    It  was  early  remarked  by  J.  D.  Whitney  that  the 

^  W.  M.  Courtis,  "  On  Silver  Islet, "  Engineering  and  Mining  Jouimal, 
Dec.  21,  1878.     Trans.  Amer.  Inst.  Min.  Eng.,  V.  474. 

E.  D.  Ingall,  Geol.  Survey  of  Canada,  1887-88,  p.  27,  H. 

F.  A.  Lowe,  "  The  Silver  Islet  Mine,"  etc.,  Engineering  and  Mining 
Journal,  Dec.  16,  1882,  p.  321. 

T,  MacFarlane,  "Silver  Islet,"  Trans.  Amer.,  Inst.  Min.  Eng.,  VIII.  226. 
Canadian  Naturalist,  IV.  38. 

McDermott,  Engineering  and  Mining  Journal,  January,  1877. 


ON  THE  FILLING  OF  MINERAL    VEINS.  43 

lead  was  usually  associated  with  the  gneis-,  *he  copper  with 
the  diabase. 

1.04.07.  From  instances  like  these  it  is  inferred  that  the 
ores  were  derived  each  from  its  own  walls,  and  by  just  such  a 
leaching  action  by  cold  surface  waters  as  is  outlined  above. 
As  opposed  to  this,  it  has  usually  been  claimed  that  each  par- 
ticular wall  exerted  a  peculiar  selective  and  precipitating  ac- 
tion on  the  metals  found  adjacent  to  it  and  none  on  the  others, 
so  that  if  a  solution  arose  carrying  both  sets,  each  came  down 
in  its  particular  surroundings  while  the  others  escaped.  Dr. 
W.  P.  Jenney  has  called  the  writer's  attentioo  to  such  a  case. 
The  Head  Center  mine,  in  the  Tombstone  district,  Arizona,  is 
on  a  vein  which  pierces  slates,  and  in  one  place  forty  feet  of 
limestone.  In  the  slates  it  carried  high-grade  silver  ores,  with 
no  lead,  but  in  the  limestone,  lead-silver  ores.  A  rock  like 
limestone  might  well  exercise  a  precipitating  action,  which, 
however,  we  cannot  attribute  to  rocks  composed  of  the  more 
inert  silicates.  Again,  it  has  been  said  that  the  solutions  com- 
ing from  below  have  varied  in  different  portions  of  the  vein  or 
at  different  periods.  An  earlier  opening  would  thus  be  filled 
with  one  ore,  a  later  opening  with  another.  This  is  hypothet- 
ical, but  has  been  advanced  for  Klausen  by  Posepny.^  A  fur^ 
ther  general  objection  to  the  first  interpretation  of  lateral  se- 
cretion is  the  weak  dissolving  power  of  cold  surface  waters,  and 
this  is  a  very  serious  one. 

1.04.08.  As  opposed  to  the  second  interpretation,  it  may  be 
advanced  that  precipitation  in  a  cavity  at  a  great  depth  would 
be  retarded  by  the  heat  and  the  pressure,  to  just  that  extent  to 
which  solution  in  the  neighboring  walls  would  be  aided.  The 
temperature  and  pressure  being  practically  the  same,  the  ten- 
dency to  remain  in  solution  would  be  great  until  the  minerals 
had  reached  the  upper  regions  and  filled  the  cavity  by  ascen- 
sion. Under  such  circumstances  ores  would  only  be  deposited 
below,  by  some  such  action  as  replacement.  To  the  third 
interpretation  no  theoretical  objections  can  be  made. 

1.04.09.  Infiltration  by  Ascension. — On  the  side  of  infiltra- 
tion by  ascension,  if  two  veins  or  sets  of  veins  were  found  in 
the  same  wall  rock,  but  with  different  kinds  of  ores  and  miner- 
als, the  conclusion  would  be  irrefutable  that  the  respective  so- 

^  Archiv.  f.  Praktische  Geologie,  p.  482. 


44  KEMP'S  ORE  DEPOSITS. 

lutions  which  formed  them  had  come  from  two  different  sources 
below.  Thus  at  Butte,  Mont.,  there  is  a  great  development  of 
a  dark,  basic  granite.  It  contains  two  series  of  veins,  of  which 
one  produces  copper  sulphides  in  a  siliceous  gangue,  while 
around  this  series,  to  the  south,  west  and  north  the  veins  yield 
sulphides  of  silver,  lead,  zinc,  and  iron,  also  in  a  siliceous 
gangue,  but  abundantl}^  associated  with  manganese  minerals, 
especially  rhodonite.  No  manganese  occurs  in  the  copper  belt, 
nor  is  any  copper  found  in  the  silver  belt.  Such  results  could 
originate  only  in  different,  deep-seated  sources.  Again,  at 
Steamboat  Springs,  Nov.,  and  Sulphur  Bank,  Cal.,  the  hot 
springs  are  still  in  action  and  are  bringing  their  burdens 
of  gangue  and  ore  to  the  surface.  The  former  has  afforded 
a  long  series  of  metals,  the  latter  chiefly  cinnabar.  G.  F. 
Becker^  has  shown  that  the  cinnabar  probably  comes  up  in 
solution  with  alkaline  sulphides. 

1.04.10.  Replacement. — The  conception  of  replacement  is 
one  that  has  been  applied  of  late  years  by  some  of  the  most  re- 
liable observers.  About  1873  it  appears  to  have  been  first  ex- 
tensively developed  by  Franz  Posepny,  an  Austrian  geologist, 
in  relation  to  certain  lead-silver  deposits  at  Raibl,  in  the  Prov- 
ince of  Kaernthen.  At  nearlj-  the  same  time  it  was  suggested  by 
Pumpelly,  then  State  Geologist  of  Missouri,  to  Adolph 
Schmidt,  who  was  engaged  in  studying  the  iron  deposits  of 
Pilot  Knob  and  Iron  Mountain  (see  Examples  11  and  11a), 
and  by  Schmidt  it  was  considered  applicable  to  them.^  Some 
ten  years  later  J.  S.  Curtis,  at  the  suggestion  of  S.  F.  Emmons, 
based  his  explanation  of  the  formation  of  the  Eureka,  Nev., 
lead-silver  deposits  on  the  same  idea,  and  according  to  Em- 
mons (1886)  it  holds  good  for  Leadville.  R.  D.  Irving,  who 
credited  Pumpelly  with  bringing  it  to  his  attention,  published 
in  1886  an  explanation  of  the  hematite  ores  of  the  Penokee- 
Gogebic  range  (Example  9c),  in  which  the  idea  is  applied,  and 
Van  Hise  has  since  elaborated  it.  In  the  process  of  replace- 
ment no  great  cavity  is  supposed  to  exist  previously.  There 
is    little,    in   fact,    but    a    circulation    or    percolation  of  ore- 


'  G.  F.  Becker,  "Natural  Solutions  of  Cinnabar,  Gold,  and  Associated 
Sulphides,"  Amer.  Jour.  Sci.,  III.,xxxiii.  199 ;  Eighth  Ann.  Rep.  Director 
U.  S.  Geol  Survey.  Monograph  XIII. ,  U.  S.  Geol.  Survey,  p.  343. 

^  "Iron  Ores  and  Coal  Fields,"  Missouri  Geol.  Survey,  1873. 


ON  THE  FILLING  OF  MINERAL    VEINS.  45 

bearing  solutions  which  exchange  their  metallic  contents, 
molecule  by  molecule,  for  the  substance  of  the  rock  mass. 
We  would  not  ordinarily  expect  the  ore  body  to  be  as  sharply 
defined  against  the  walls  as  when  it  fills  a  fissure,  but  rather  to 
fade  into  barren  material.  Thus  rock  may  be  impregnated  but 
not  entirely  replaced,  and,  while  apparently  unchanged,  yet 
carry  valuable  amounts  of  ore.  Some  of  the  ores  of  Aspen, 
Colo.  (Example  30d),  are  at  times  only  to  be  distinguished  by 
assay  from  the  barren  limestones.  Yet  decomposition  may 
bring  out  the  limits  of  each. 

1.04.11.  The  chemistry  of  the  replacement  process  is  none 
too  well  understood,  but  it  presents  fewer  difficulties  when  ap- 
plied to  a  soluble  rock,  like  limestone  or  dolomite,  than  when 
rocks  composed  of  silicates  and  quartz  have  given  way  to  ores. 
Acid  solutions  would  readily  yield  to  calcium  carbonate;  but 
if  the  metals  are  present  as  sulphides,  some  reducing  agent, 
such  as  organic  matter,  is  necessary  in  order  to  change  the  me- 
tallic sulphate  to  sulphide.^  Or  else,  if  the  metallic  sulphides 
come  up  in  solution  with  alkaline  sulphides,  some  third  agent 
is  needed  to  remove  the  calcium  carbonate,  pari  passu  just  be- 
fore the  metallic  sulphide  is  precipitated.  It  must  be  con- 
fessed that  for  enormous  bodies  of  ore,  like  those  of  Leadville, 
the  small  amount  of  organic  matter  present  seems  hardly  equal 
to  the  task  assigned  it,  and  the  delicate  balance  of  the  latter 
case — causing  deposition  to  tread  so  closely  on  the  heels  of  rock 
removal,  in  order  to  avoid  assuming  an  extended  cavitj^ — 
makes  it  appear  that  the  entire  chemistrj^  of  the  process  is  per- 
haps hardly  understood. 

1.04.12.  When  silicate  rocks  are  replaced,  leaving  a  sili- 
ceous gangue,  the  process  may  have  been  somewhat  as  sug- 
gested by  R.  C.  Hills  for  the  mines  of  the  Summit  district,  Rio 
Grande  County,  Colorado.^  Alkaline  solutions  remove  silica 
and  have  slight  action  on  silicates,  but  solutions  acid  with 
sulphuric  acid  attack  silicates,  such  as  feldspar  and  biotite, 
change  the  alumina  to  a  soluble  sulphate,  and  cause  the 
separation  of  free  silica.      In   the  alteration  products  abun- 

*  Compare  S.  F.  Emmons,  "  On  the  Replacement  of  Leadville  Lime- 
stones and  Dolomites  by  Sulphides/'  Monograph  XIL,  U.  S.  Geol.  Survey, 
p.  563. 

'  See  Proc.  Colo.  Sci.  Soc,  Vol.  I.,  p.  20. 


46  KEMP'S  ORE  DEPOSITS. 

dant  opportunity  would  be  afforded  for  the  precipitation  of 
sulphides,  which  would  in  part  at  least  replace  the  rock. 
Along  a  crack  or  line  of  drainage  definite  walls  would  thus 
easily  fade  out.  Such  phenomena  are  afforded  by  innumerable 
ore  deposits^  and  often  come  under  the  notice  of  every  one 
familiar  with  mining.  Yet  we  cannot  but  hope  that  in  the 
future  our  knowledge  of  the  chemical  reactions  involved  will 
be  increased. 

It  may  again  be  stated  that  the  formation  of  ore  deposits  has 
proceeded  with  great  slowness,  and  that  the  solutions  bringing 
the  metals  have  been,  beyond  question,  very  dilute;  The  ex- 
tremely small  amounts  of  the  metals  which  have  been  detected 
in  relatively  large  amounts  of  igneous  rocks,  even  by  the  most 
refined  analytical  methods,  have  necessarily  made  the  progress 
of  solution  a  protracted  one.  Curtis  records  some  careful  observ- 
ations on  the  growth  of  aragonite  at  Eureka,  Nev.,  where  he 
found  that  in  three  weeks,  so  long  as  wet  by  a  drop  of  water, 
the  crystals  increased  in  one  case  as  a  maximum  five-eighths  of 
an  inch,  and  in  another  three-eighths.  But  this  was  where 
the  whole  inclosing  mass  of  rock  consisted  of  the  compound 
deposited. 

^  See  R.  W.  Eaymond,  discussion  of  S.  F.  Emmons'  "Notes  on  the 
Geology  of  Butte,   Mont,"   Trans.  Amer.   Inst   Min.  Eng.,  XVI.,  p.  59, 

1887. 


CHAPTER  V. 

ON  CERTAIN   STRUCTURAL   FEATURES   OP  MINERAL  VEINS. 

1.05.01.  Banded  Structure.— Mmeral  veins  sometimes  ex- 
hibit a  banded  strucnre,  by  which  is  understood  the  arrange- 
ment of  the  ore  and  gangue  in  parallel  layers  that  correspond 
on  opposite  walls.  They  are  most  conspicuous  where  the  walls 
are  well  defined.  The  solutions  which  have  brought  the  min- 
erals have  varied  from  time  to  time,  and  the  precipitated  coat- 
ings ^correspond  to  these  variations.  They  alternate  from 
gangue  to  ore,  it  may  be,  several  times  repeated.  The  ore 
may  be  in  small  scattered  masses  preserving  a  distinct  lineal 
arrangement  in  the  midst  of  the  barren  quartz,  calcite,  barite, 
fluorite,  siderite,  etc. ,  or  itself  be  so  abundant  as  to  afford 
continuous  parallel  streaks.  The  commonest  ores  so  observed 
are  pj'rite,  chalcopyrite,  galena,  blende,  and  the  various  sul- 
phides of  silver.  The  veins  of  the  Reese  River  district,  in  Ne- 
vada, furnish  good  illustrations  of  alternating  ruby  silver  ores 
and  quartz.  Those  of  Gilpin  County,  Colorado  (Example  17a), 
afford  alternations  of  pyrite,  chalcopyrite,  and  gangue.  (See 
figures  in  Endlich's  report,  Hayden's  Surveij,  1873,  p.  280.) 
The  Bassick  mine,  in  Colorado,  has  pebbles  remarkably  coated. 
Figure  6  shows  a  vein  at  Newman  Hill,  near  Rico,  Colo. 

Banded  veins,  however,  except  of  a  rude  character,  are  not 
common  in  this  country.  They  have  received  much  more  at- 
tention in  Germany,  where,  especially  near  Freiberg,  they  show 
remarkable  perfection.  The  famous  Drei  Prinzen  Spat  \^ein. 
Fig.  by  Von  Weissenbach  and  copied  in  many  books,  has 
ten  corresponding  alternations  of  six  different  minerals  on 
each  wall.  Banded  structure,  whether  of  veins  or  vuggs  or 
stalactites,  etc.,  has  been  called  ''crustification"  by  Posepny, 
who  considers  it  an  infallible  symptom  of  deposition  from 
solution. 


48 


KEMP'S  ORE  DEPOSITS. 


1,05.02.  Aline  of  cavities,  or  vuggs,  is  often  seen  at  the 
central  portion  of  a  vein,  into  which  crystals  of  the  last-formed 
minerals  protrude,  forminj^;  a  comb  (see  Fig.  6).  These  may  pro- 
ject into  each  other  and  interlock — especially  in  quartz — form- 
ing a  comb  in  comb.  The  same  may  occur  between  side  lay- 
ers. These  cavities  are  a  most  prolific  source  of  finely  crystal- 
lized minerals.  If,  after  the  fissure — perhaps  at  the  time  small 
— has  become  once  filled,  subsequent  movement^:  take  place,  it 
may  strip  the  vein  from  one  wall  and  cause  a  new  series  of 
minerals  to  be  deposited,  with  the  previously  formed  vein  on 
one  side  and  the  wall  rock  on  the  other.  This  occasions  un- 
symmetrical  fillings.    But  it  may  also  happen  that,  with  other- 


West 


East 


Fig.  Q.— Banded  Vein  at  Neimnan  Hill,  near  Rico,    Colo.       After  J.   B- 

Farish,   Proc.,    Colo.    Sci.  Soc,  April  4,  1892;  Engineering 

and  Mining  Journal,  August  20,  1892. 

wise  symmetrical  fillings,  one  layer  may  be  lacking  on  one  side 
or  the  other.  Where  portions  of  the  wall  rock  have  been  torn 
off  by  the  vein  matter  in  these  secondary  movements,  they  may 
be  buried  in  the  later  deposited  vein  filling,  and  form  great 
masses  of  barren  rock  called  "horses."  The  vein  then  forks 
around  them.  If  the  ore  and  the  gangue  have  partly  replaced 
the  wall  in  deposition,  unchanged  masses  of  wall  may  also 
become  inclosed  and  afford  horses  of  a  different  origin.  An 
originally  forked  fissure  gives  an  analogous  result. 

It  is  a  curious  fact  that  veins  are  often  most  productive  just 
at  the  split.     If  the  masses  are  small,  or  if  the  vein  fills  a  shat- 


OJV  STBUGTUUAL  FEATURES  OF  MINERAL    VEINS.      49 

tered  strip  and  not  a  clean  fissure,  or  if  it  occupies  an  old  vol- 
canic conduit,  deposition  and  replacement  may  surround  un- 
changed cores  of  wall  rock  with  concentric  layers  of  ores  and 
minerals.  Thus  the  Bassick,  at  Rosita,  Colo.,  referred  to  above, 
consists  of  rounded  cores  of  andesite,  inclosed  in  five  concentric 
layers  of  metallic  sulphides.  The  Bull  Domingo,  in  the  same 
region,  exhibits  shells  of  galena  and  quartz  mantling  nodules 
of  gneiss.  Such  cores  strongly  resemble  rounded,  water-worn 
boulders,  a  similarity  which  has  suggested  some  rather  improb- 
able hypotheses  of  deposition. 

1.05.03.  Clay  Selvage. — An  extremely  common  feature  is 
a  band  of  clay,  most  often  between  the  vein  matter  and  the 
wall.  This  is  called  a  selvage,  gouge,  flucan,  clay  seam,  or 
parting.  It  may  come  in  also  between  layers  of  different  min- 
erals, and  may  even  rest  as  a  mantle  on  the  crystals  which  line 
cavities.  It  is  at  times  the  less  soluble  portion  left  by  the  de- 
cay and  removal  in  solution  of  wall  rock  (residual  clay),  at 
times  the  comminuted  material  resulting  from  the  friction  of 
moving  walls  (attrition  clay),  and  again  it  may  be  taken  up  by 
currents  and  redeposited  from  bodies  of  the  first  two  sorts. 
Such  layers  of  clay,  being  well-nigh  impervious  to  water,  may 
have  exercised  an  important  influence  in  directing  the  subterra- 
nean circulations.^ 

1.05.04.  Pinches,  Swells,  and  Lateral  Enrichments. — The 
swells  and  pinches  of  veins  have  been  referred  to  above  and  ex- 
plained. Aside  from  these  thicker  portions  of  the  ore,  it  is 
often  seen  that  the  richer,  or  even  the  workable  bodies  follow 
certain  more  or  less  regular  directions,  forming  so-called 
*' chutes."  They  probably  correspond  to  the  courses  taken  and 
followed  by  the  richer  solutions.  J.  E.  Clayton  observed  that 
they  follow  the  directions  of  the  slips,  or  striae,  of  the  walls 
rather  more  often  than  not,  and  in  the  West  this  disposition  or 
tendency  is  called  Clayton's  law.  Chute  is  sometimes  spelled 
"shoot"  or"shute."  Chimney  and  ore-course  are  synonyms 
of  chute.  Bonanza  is  used,  especially  on  the  Comstock  Lode, 
to  indicate  a  localized,  rich  body  of  ore. 

Lateral  enrichments  are  caused  by  the  spreading  of  the  ore- 
bearing  currents  sidewise  from  the  vein,  and  often  along  par- 
ticular beds  of  rock,  which  they  may  replace  more  or  less  with 
^  See  citation  from  Becker  on  the  Comstock  Lode,  2.11.19. 


50  KEMP'S  ORE  DEPOSITS. 

ore.  Beds  of  limestoue — it  may  be  quite  thin,  when  in  a  series 
composed  of  shales  or  sandstones — are  favorite  precipitants,  and 
from  such  lateral  enlargement  the  best  returns  may  be  ob- 
tained. The  valuable  ore  bodies  of  Newman  Hill,  near  Rico, 
Colo.,  whose  interesting  descriptions  by  J.  B.  Farish  and  T.  A. 
Rickard  have  already  been  several  times  cited,  are  found  as 
lateral  enrichments  along  a  bed  of  limestone  less  than  three 
feet  thick  and  embedded  in  shales.  Above  the  limestone  the 
veins  practically  cease,  as  the  fissures  become  tight  in  a  series 
of  sandstones  and  shales.  Lateral  enrichments  may  closely  re- 
semble bedded  deposits  if  the  supply  fissures  are  relatively 
small,  but  it  is  generally  safe  to  infer  the  presence  of  supply 
conduits,  although  they  may  be  obscure.  The  Potsdam  ores  of 
the  Black  Hills  are  good  illustrations. 

1.05.05.  Changes  in  Character  of  Vein  Filling. — In  dis- 
cussing the  influence  of  wall  rock  the  changes  that  occur  in 
veins  were  briefly  mentioned.  But  even  where  the  walls  re- 
main uniform  there  is  always  variation  in  contents,  and  of 
course  in  value,  from  point  to  point.  Ore,  gangue,  horses,  and 
walls  alternate  both  longitudinally  and  in  depth,  and  such 
changes  must  be  allowed  for  and  averaged  by  keeping  explora- 
tion well  in  advance  of  excavation.  Even  a  series  of  parallel 
veins  may  all  prove  fickle.  In  illustration  of  the  above  the 
Marshall  tunnel  of  Georgetown,  Colo.,  may  be  cited.  It  cut 
twelve  veins  below  their  actual  workings,  and  every  one  was 
barren  at  the  tunnel  though  productive  above.  ^ 

1.05.06.  Secondary  Alteration  of  the  Minerals  in  Veins, 
— It  has  already  been  stated  that  the  chief  ore  minerals  in  vein 
fillings  are  sulphides.  Where  these  lie  above  the  line  of  per- 
manent subterranean  water  they  are  exposed  to  the  oxidizing 
and  hydrating  action  of  atmospheric  waters,  which,  falling  on 
the  surface,  percolate  downward.  The  ores  are  thus  subjected 
to  alternating  soakings  and  dryings  which  encourage  altera- 
tion. The  sulphides  change  to  sulphates,  carbonates,  oxides, 
or  hydrous  forms  of  the  same,  and  the  metallic  contents  are  in 
part  removed  in  the  acid  waters  which  are  also  formed.  Py- 
rite,  which  is  the  most  widespread  of  the  sulphides,  becomes 
limonite,  staining  everything  with  its  characteristic  color. 
Galena  becomes  cerussite  or  anglesite.     Blende  affords  cala- 

*  J.  J.  Stevenson,  Wheeler's  Survey,  Geology,  Vol.  III.,  p.  351, 


ON  8TBUGTUBAL  FEATURES  OF  MINERAL    VEINS,      51 

mine  and  smifchsonite.  Copper  ores,  of  which  the  usual  one  is 
chalcopyrite,  change  to  malachite,  azurite.  chrysocolla,  cuprite, 
and  melaconite,  and  to  the  sulphide,  chalcocite.  The  silver  sul- 
phides afford  cerargyrite.  The  rarer  metals  alter  to  correspond- 
ing compounds  of  less  frequency.  These  upper  portions  are 
also  more  cellular  and  porous,  being  at  times  even  earthy. 
The  rusty  color  from  the  presence  of  limonite  often  marks  the 
outcrop  and  is  of  great  aid  to  the  prospector.  It  has  been  called 
the  iron  hat,  or  gossan.  This  feature  has  important  economic 
bearings.  The  character  of  ores  may  entireh'  change  at  a  defi- 
nite point  in  depth,  and  the  later  products,  if  not  lower  in 
grade,  as  is  often  the  case,  may  demand  different,  perhaps  more 
difficult,  modes  of  treatment.  Oxidized  ores  are  the  easiest  to 
smelt,  and  the  desirability  of  careful  exploration  before  indulg- 
ing in  too  confident  expectations  may  be  emphasized.  As  exam- 
ples, the  Ducktown  copper  deposits  (See  Example  16),  the 
Leadville  silver  mines  (Example  30),  the  southwest  Virginia 
zinc  deposits  (Example  26),  ths  copper  and  silver  veins  at 
Butte,  Mont.  (Example  17),  and  others  in  Llano  County, 
Texas  (Example  176),  may  be  cited.  At  Ducktown  a  con- 
siderable thickness  of  chalcocite,  melaconite,  and  carbonates 
accuraulated  just  at  the  waterline  and  abruptly  changed  to 
low-grade,  unworkable  pyrite  and  chalcopyrite  below  it.  At 
Bonsacks,  near  Roanoke,  Va.,  very  rich,  easily  treated, earthy 
limonite  and  smithsonite  (30  to  40  per  cent,  zinc)  passed  into  a 
refractory,  low  grade  (15  to  20  percent,  zinc),  intimate  mixture 
of  blende  and  pyrite.  Excavations  in  dry  districts  may  not 
reach  the  watfer  line  for  great  depths.  Thus  at  Eureka,  Nev., 
in  the  rainless  region  of  the  Great  Basin,  the  oxidized  ores  con- 
tinue to  900  feet  or  more. 

It  is  worthy  of  remark  in  this  connection  that  possibly  some 
deposits  of  oxidized  ores  may  have  been  formed  originally  as 
such.  Wendt  has  argued  this  for  the  copper  mines  of  the  Bis- 
bee  district,  Arizona;  but  in  this  case  recent  exploration  has 
established  the  former  presence  of  sulphides.  (See  Example 
206.)  If  oxidized  ores  are  now  found  below  the  water  line,  it 
may  indicate  a  depression  of  the  rocks  from  a  previous,  higher 
position.  R.  C.  Hills  has  brought  out  a  very  interesting  in- 
stance of  the  concenti-ation  of  gold  and  silver  in  the  lower 
part  of  the  oxidized  zone,  or  at  least  at  a  considerable  depth 


52  KEMP'S  ORE  DEPOSITS. 

beiow  the  outcrop.  The  upper  portion  of  the  vein,  in  this 
case  with  a  quartz  gangue,  was  impoverished.  The  gold  is 
thought  to  have  been  carried  down  in  solution  with  ferrous 
and  ferric  sulphates,  which  were  decomposed  by  feldspar, 
while  the  precious  metal  was  thrown  down.  The  ore  bodies 
lie  in  the  Summit  district,^   Rio  Grande   County,    Colorado. 

1.05.07.  The  waters  of  mines  which  have  opened  up  and 
exposed  sulphides  to  oxidation  are  often  charged  with  sul- 
phuric acid  and  even  metallic  salts.  This  is  especially  true  of 
mines  in  copper  sulphides,  and  the  pumps  are  much  corroded. 
In  instances  considerable  metallic  copper  has  been  removed  by 
passing  the  mine  drainage  over  scrap  iron,  as  at  Ducktown, 
Tenn.,  and  as  has  been  introduced  at  Butte,  Mont.  Mine 
timbers  have  been  preserved  very  long  periods  by  the  deposi- 
tion of  copper  on  them,  because  of  their  reducing  action  on  the 
solutions.  Pumps  and  timbers  placed  by  the  Romans  in  the 
Rio  Tinto  mines,  in  Spain,  are  still  in  good  preservation. 
Even  gold  has  been  detected  in  Australian  mine  waters.^ 

1.05.08.  Electrical  Activity. — Among  the  writers  of  fifty 
or  sixty  years  ago,  electrical  or  galvanic  action  was  a  favorite 
theoretical  precipitant  of  ores  in  veins,  and  careful  experi- 
ments were  made  in  England  and  Germany  to  detect  it.  By 
connecting  the  opposite  ends  of  a  vein  with  a  wire,  in  which 
was  a  galvanom.eter,  the  attempt  was  made  again  and 
again  to  establish  the  existence  of  galvanic  action.  At  times 
the  results  gave  some  grounds  for  belief,  but  at  others  they 
were  contradictory  or  uncertain,  so  that  no  very  definite  or 
reliable  conclusions  were  established  Other  experiments 
were  made  in  Germany  about  1844,  by  Reich,  while  lately 
quite  elaborate  investigations  have  been  carried  out  by  Dr. 
Carl  Barus  on  the  Comstock  Lode,  and  at  Eureka,  Nev. 
Great  difficulties  are  met  in  preserving  the  necessary  insula- 
tion throughout  the  wet  and  devious  underground  workings. 

^  R.  C.  Hills,  Proc.  Colo.  Sci.  Soc,  Vol.  I.,  p.  32;  S.  F.  Emmons,  quot- 
ing Hills,  Engineering  and  Mining  Journal,   June  9,  1883. 

For  a  very  complete  discussion  of  the  alteration  of  ore  deposits  above 
the  ground  water  and  of  the  formation  of  gossan  minerals,  see  R.  A.  F. 
Penrose,  Jr.,  "The  Superficial  Alteration  of  Ore  Deposits,"  Journal  of 
Geology,  II.  288,  1894. 

'  See  School  of  Mines  Quarterly,  Vol.  XI.,  364,  for  review  of  literature 
bearing  on  this  subject. 


ON  STRUCTURAL  FEATURES  OF  MINERAL    VEINS.      53 

and  amid  such  surroundings  in  detecting  the  currents,  which 
would  be  necessarily  small.  With  Barus  the  thesis  was  not 
alone  to  establish  a  galvanic  action,  such  as  might  be  a  precipi- 
tating agency,  but  also  to  observe  what  effect,  if  any,  was  ex- 
erted by  the  intervention  of  an  ore  body  on  the  normal  terres- 
trial currents.  Had  this  latter  been  proved  of  sufficient  amount, 
the  existence  of  such  bodies  might  be  indicated  by  plotting 
electrical  observations.  While  in  some  respects  of  interest,  the 
results  of  Dr.  Barus  are  not  very  decisive,  and  this  line  of  in- 
vestigation is  hardly  to  be  considered  a  promising  one.  The 
importance  attached  to  it  in  former  years  may  be  illustrated  by 
these  words  of  De  la  Beche,  one  of  the  ablest  of  English 
writers,  in  1839,  Speaking  of  veins  in  general,  after  discussing 
those  of  Cornwall  in  particular,  he  says:  "Mineral  veins  result 
from  the  filling  of  fissures  in  rocks  by  chemical  deposits,  from 
substances  in  solution  in  the  fissures,  such  deposits  being 
greatly  due  to  electro-chemical  agency."  The  influence  of  ter- 
restrial magnetism  upon  the  distribution  of  mineralized  dis- 
tricts has  been  urged  by  T.  F.  Van  Wagenen,  w^ho  endeavors 
to  show^  for  the  Cordilleran  region  of  North  America  that  the 
productive  areas  lie  along  mean  magnetic  curves  and  that  they 
are  separated  by  barren  belts.  The  productive  belts  are  thought 
to  converge  at  the  magnetic  pole  of  the  earth  north  of  Hudson 
Bay.^ 

^  Theo.  F.  Van  Wagenen,  "System  in  the  Location  of  Mining  Districts," 
School  of  Mines  Quarterly,  January,  1898,  p.  109. 


CHAPTER  VI. 

THE    CLASSIFICATION    OF    ORE    DEPOSITS — A  REVIEW    AND    A 
SCHEME  BASED  ON  ORIGIN. 

1.06.01.  In  the  classification  of  ore  deposits  the  same  syste- 
matic arrangement  is  not  to  be  expected  as  in  the  grouping  of 
plants,  animals,  or  minerals.  Ore  deposits  have  not  the  under- 
lying affinities  and  relationships  of  living  organisms  nor  of  defi- 
nite chemical  compounds.  The  series  of  objects  is  too  diverse, 
and,  in  the  nature  of  the  case,  the  standards  of  appeal  must  be 
different.  The  subject  is,  however,  one  of  great  practical  impor- 
tance as  well  as  of  great  scientific  interest.  A  vocabulary  of 
intelligible  terms  is  indispensable  for  description  and  compari- 
son, and,  under  our  mining  laws,  often  for  valid  titles,  while 
as  a  vehicle  for  the  spread  of  knowledge  and  reasonable  con- 
ceptions regarding  these  phenomena,  its  importance  cannot  be 
overestimated. 

1.06.02.  All  schemes  of  classification  rest  on  these  princi- 
ples: form,  origin — or  the  genetic  principle  (including  method, 
relative  time  of  origin  as  contrasted  with  the  w^alls,  etc.) — state 
of  aggregation,  and  mineral  contents.  Of  these,  the  principle  of 
form  is  usually  esteemed  the  weightiest,  and  is  given  the  great- 
est prominence,  partly  because  it  has  been  thought  to  be  the 
one  most  closely  affecting  exploitation,  and  partly  because  it 
involves  less  that  is  or  has  been,  up  to  very  recent  times,  more 
or  less  hypothetical.  Yet  form  is  largely  fortuitous,  and  it  has, 
of  course,  no  law,  while,  with  sufficient  knowledge,  the  genetic 
principle  is  the  one  giving  a  far  more  thoroughly  scientific 
basis.  Everyone,  in  opening  up  or  searching  for  an  ore  body, 
must  be  influenced  by  some  hypothesis,  either  of  shape  or  of 
origin.  It  is  the  conviction  of  ihe  writer  that,  with  all  6ur  de- 
ficiencies of  knowledge,  the  genetic  principle  is  also  the  best 
guide,  even  in  practical  development. 


CLASSIFICATION  OF  ORE  DEPOSITS.  55 

1.06.03.  Very  early  in  the  development  of  mining  litera- 
ture the  distinction  was  made  between  those  ore  bodies  which 
are  parallel  to  the  stratification  and  those  which  break  uncon- 
formably  across  it.  This  took  place  long  before  the  epoch-mak- 
ing time  of  Werner,  and  even  before  the  conception  of  the  rela- 
tive ages  of  strata  had  been  at  all  generally  grasped.  Thus 
among  the  Germans  we  find  the  terms  "Lager"  and  *'Flotze"^ 
on  the  one  side,  being  set  off  in  contrast  to  "Gang"  (vein) 
on  the  other.  Werner,  writing  in  1791,  quotes  Von  Oppel's 
distinctions  between  Flotze  (strata  beds)  and  Gauge  (veins), 
which  were  published  in  1749;  but  without  doubt,  as  mining 
terms,  they  go  much  further  back.  Beyond  this  simple  indica- 
tion of  the  views  of  the  older  writers,  no  attempt  will  be  made 
here  to  quote  authorities  earlier  than  1850.  This  is  justifiable, 
because  the  important  works,  like  De  la  Beche's  Geology  of 
Cornwall  and  Devon,  and  Kenwood's  Metalliferous  Deposits 
of  Cornwall  and  Devon,  are  rather  discussions  of  veins  than 
systematic  attempts  at  classification. 

1.06.04.  In  Appendix  I.  will  be  found  the  principal  schemes 
of  classification  which  have  thus  far  been  suggested.  They  are 
grouped  according  to  certain  relationships  and  similarities  that 
run  through  them.     The  scheme  here  given  finds  its  natural 

^  Lager  and  Flotze  are  diflStcult  to  render  into  English  while  retaining 
their  native  shades  of  meaning  The  later  writers  in  Germany  (Serlo, 
Gatzchmann,  Von  Groddeck,  Kohler)  define  them  as  being  interbedded 
bodies,  each  later  than  the  foot  wall  in  formation,  and  older  than  the 
hanging;  and  that  Lager  are  much  more  limited  in  horizontal  extent 
than  Flotze  R.  Wabner  shows,  however,  in  the  Berg.  -  u.  Hut.  Zeitung, 
Jan.  2,  1891,  p.  1,  that  writers  in  the  earlier  part  of  the  century  did  not 
entirely  restrict  the  term  Lager  as  regards  age  relative  to  the  foot  and 
hanging,  but  applied  it  to  ore  bodies,  which  follow  the  general  bedding, 
although  they  may  have  been  introduced  much  later  than  the  formation 
of  the  walls.  Thus  the  frequent  occurrence  of  lead  ores  in  limestone  along 
certain  beds  (southeast  Missouri  for  example)  would  be  called  Lager. 
We  would  apply  the  terms  impregnation,  or  dissemination,  or  bed-vein,  to 
such.  Flotze  we  would  call  stratum,  and  Lager,  as  defined  by  the  later 
authors  "bed"  or  "seam."  Werner,  for  instance,  in  his  classification  of 
the  rock  formations  of  the  globe,  made:  I.  Urgebirge  (Primitive,  Primary, 
etc.,  having  no  fossils).  II.  Secondary,  subdivided  into  A.  Ueber- 
gangsgebirge  (transitional,  more  or  less  metamorphosed  sediments,  but 
fossiliferous).  B.  Flotzgebirge  (unaltered  strata).  From  this  the  mean- 
ing of  Flotz  may  be  grasped.  By  contrast,  a  magnetite  lens  is  a  good 
illustration  of  Lager. 


56  KEMP'S  ORE  DEPOSITS. 

place  as  No.  17,  and  at  the  time  that  it  was  first  prepared  it  was 
unique  in  being  a  purely  genetic  one,  except  that  one  by  F.  D. 
Power,  which  appeared  in  Melbourne  the  same  year,  ran  along 
the  same  lines.  The  literature  of  the  next  few  years  proved, 
however,  that  the  subject  was  active  in  many  minds,  and  other 
schemes  were  independently  published  in  different  parts  of  the 
world,  which  were  conceived  from  the  same  point  of  view.  In 
the  one  below,  the  four  important  methods  of  origin,  viz.,  the 
igneous,  the  methods  of  precipitation  from  solution  or  by  depo- 
sition from  suspension  or  by  deposition  as  residual  concentra- 
tions, are  made  fundamental  and  then  the  ore-bodies  belonging 
under  each  are  referred  so  far  as  possible  to  well-recognized  and 
familiar  geological  phenomena.  The  close  analogy  of  this 
grouping  in  some  of  its  particulars  to  the  commonly  accepted 
classification  of  rocks,  will  beat  once  apparent,  and  our  general 
knowledge  of  rocks  may  be  used  to  throw  light  upon  the  ore 
deposits,  but  the  latter  with  the  exception  of  a  few  involving 
iron,  are  never  in  sufficient  amount  to  be  considered  particular 
forms  of  rock,  in  and  of  themselves.  The  scheme  is  also  the 
natural  result  of  the  general  exposition  of  the  subject  in  the 
preceding  pages,  which  have  consistently  led  up  to  it.  Certain 
obscure  ore  bodies,  which  are  not  well  understood,  receive  spe- 
cial mention  after  the  general  discussion. 

1.06.05.     J.  F.  Kemp,  1892.     Eevised  from  the  School  of 
Mines  Quarterly,  November,  1892. 

I.  Of  Igneous  Origin.  Excessively  basic  develop- 
ments of  fused  and  cooling  magmas.  Peridotite, 
forming  iron  ore  at  Cumberland,  Rhode  Island.^ 
Titaniferous  magnetite,  Jacupiranga,  Brazil  f  in 
Minnesota  gabbrosf  in  Adirondack  gabbros;*  in 
Swedish  and  Norwegian  gabbros.^  Nickeliferous 
pyrrhotite.^    Chromite.'    Corundum.' 

»  M.  E.  Wadsworth,  Bull.  Mus.  Comp.  Zool,  1880,  VII. 
^  O.  A,  Derby,  Amer.  Jour.  Sci.,  April,  1891. 

'  N.  H.  Winchell,  Tenth  Ann.  Rep  Minn.  Geol.  Survey,  pp.  80-83,  Bull. 
VI.  of  same  survey,  p.  135. 

*  J.  F.  Kemp,  Bull.  Geol.  Soc.  Amer.,  V.  222,  1894.  XIX.  Annual  Rep. 
Dir.  U.  S.  Geol.  Survey.      (In  press,  March,  1899. ) 

'  J.  H.  L.Vogt,  Geol.  Foren.  i.  Stockholm  Forhand,  XIII.,  476,  May,  1891. 
English  abstract  and  review  by  J.  J.  H.  Teall,  Geol.  Mag.,  February,  1892 
See  also  Zeitschr.  fur  Praktische  Geologic,  I. ,  4. 

*  See  references  under  paragraph  1.06.08  below. 
^  See  references  under  paragraph  1.06.13. 


CLASSIFICATION  OF  ORE  DEPOSITS.  57 

.  II.  Deposited  from  solution. 

1.  Surface    precipitations,    often    forming 
beds  and  caused  by — 

(a)  Oxidation.  Bog  ores.  Ferruginous  oolites, 
as  in  some  Clinton  ores.^ 

(6)  Sulphurous  exhalations  from  decaying  or- 
ganic matter,  etc.     (Pyrite.) 

(c)  Reduction,  chiefly  by  carbonaceous,  organic 

matter.     (Pyrite  from  ferrous  sulphate.) 

(d)  Evaporation,  cooling,  loss  of  pressure,    etc. 

Hot    spring    deposits,    as   at   Steamboat 
Springs,  Nev.^ 

(e)  Secretions  of  living  organisms.     (Iron  ores 

by  algse.^ 

Note. — These  same^  causes  of  precipitation  operate  in  sub- 
terranean cavities,  although  not  again  specially  referred  to. 

2.  Disseminations  (impregnations)  in  par- 
ticular beds  or  sheets,  because  of — 

(a)  Selective  porosity.     (Silver  Cliff,  Colo.,  sil- 
ver ore   in  porous  rhyolite.*     Amygda- 
loidal  fillings  as  in  copper-bearing  amyg- 
daloid.    Keweenaw  Point,  Mich. ;   Santa 
Rita,  N.  M.*^      Impregnations  of  porous 
Sandstone  as  at  Silver  Reef,  Utah.^ 
(6)  Selective  precipitation  by  calcareous  matter. 
Potsdam  or  siliceous  gold  ores.   Black 
Hills,  S.  D.^ 
3o  Filling  joints  caused  by  cooling  or  dry- 
ing (Mississippi  Valley  gash  veins  in 
part). 

*  C,  H.  Smyth,  Jr.,  Amei\  Jour.  Set.,  June,  1892,  p.  487. 

«  G.  F.  Becker,  Monograph  XIIL,  U.  S.  Geol.  Sm-vey,  pp.  331,  468;Laur, 
Ann.  des  Mines,  1863,  p.  421;  J.  Leconte,  Amer.  Jour.  Sci.,  June,  1883,  p. 
424,  July,  p.  1 ;  W.  H.  Weed,  idem,  August,  1891,  p.  166. 

^  Sjogrun,  Berg.-  und  Hutt.  Zeit.,  1865,  p.  116. 

*  Clark,  Engineering  and  Mining  Journal,  Nov.  2,  1878,  p.  314. 

*  A.  F.  Wendt,  Trans.  Amer.  Inst.  Min.  Eng.,  XV.,  27, 
«  C.  M.  Rolker,  idem,  IX.,  21. 

'  J.  D.  Irving,  Annals  N.  Y.  Acad.  Scl,  XII.  Part  II,  1899.  Other  cita 
tions  will  be  found  under  2,01.03. 


58  KEMP'S  ORE  DEPOSITS. 

4.  Occupying  chambers  (caves)  in  lime- 
stone.    (Cave  Mine,  Utah. ^ ) 

5.  Occupying  collapsed  (brecciated)  beds, 
caused  by  solution  and  removal  of  sup 
port,  or  from  dolomitization  of  lime 
stone.  (Southwest  Missouri  zinc  depos- 
its.^ Occupying  cracks  at  Monoclinal 
bends,  Anticlinal  summits.  Synclinal 
troughs,  often  with  replacement  of  walls. 
(Gash  veins  in  part;  galena  deposits 
at  Mine  la  Motte,  Missouri;  zinc 
blende  deposits  in  the  Saucon  Valley, 
Pennsylvania.^)      Elkhorn  Mine,  Mont. 

6.  Occupying  shear-zones,  or  dynamically 
crushed  strips  along  faults,  whose  dis- 
placement may  be  slight,  closely  related 
to  No.  8.     (Butte,  Mont.)* 

7.  True  veins  filling  an  extended  fissure, 
often  with  lateral  enlargements.  See 
also  under  5. 

8.  Occupying  volcanic  necks,  in  agglom- 
erates. (Bassick  Mine,  near  Rosita, 
Colo.)^ 

9.  Replacements  in  troughs  of  some  im- 
pervious rock  or  rocks.  (Lake  Superior 
hematites.)^ 

10.  Contact  deposits.  Igneous  rocks  always 
form  one  wall.    Fumaroles.     (Greisen.) 

*  J.  S.  Newberry,  School  of  Mines  Quarterly,  March,  1880.  See  also  J. 
P  Kimball,  on  Santa  Eulalia,  Chihuahua,  Amer.  Jour.  Sei.,  II.,  xlix.  101. 

^  F  L.  Clerc,  Lead  and  Zinc  Ores  in  Southwest  Missouri  Mines,  Carthage. 
Mo.,  1887;  A,  Schmidt,  Missouri  Oeol.  Survey,  1874,  p.  384.  See  later 
papers  cited  under  Example  25. 

"  F.  L.  Clerc,  Mineral  Resources,  1882,  p.  361 ;  H.  S.  Drinker,  Trans. 
Amer.  Inst.  Min.  Eng.,  I.,  367. 

*  S.  F,  Emmons,  Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  49;  W.  P.  Blake, 
Idem,  XVI.,  65.     Butte  Special  Folio,    U.  S.  Geol.  Survey. 

•  C.  W.  Cross,  Proc.  Colo.  Sei.  Soc,  1890,  p.  269.  S.  F.  Emmons,  XVIL 
Rep.  U.  S.  Geol.  Surv.,  Part  II.,  p.  430. 

•  C.  R.  Van  Hise,  Amer.  Jour.  Sei.,  February,  1892,  p.  116.  Monograph 
XXVIII  U.  S.  Geol.  Surv. 


CLASSIFICATION  OF  ORE  DEPOSITS.  59 

11.  Segregations   formed   in   the  alteration 
of  igneous  rock.     (Chromite  in  serpen- 
tine.) 
III.  Deposited  from  Suspension.     Residual  Deposits. 

1.  Metalliferous  Sands  and  Gravels, 
whether  now  on  the  surface  (placers, 
magnetite  beach'sands),  or  subsequently 
buried.  (Deep  gravels, magnetite  lenses?) 

2.  Residual  Concentrations,  left  by  the 
weathering  of  the  matrix.  (Iron  Moun- 
tain, Mo.,  hematite  in  part.^) 

1.06.06.  It  is  believed  that  under  the  above  heads  are  in- 
cluded all  the  forms  of  ore  bodies  which  constitute  well-recog- 
nized and  fairly  well-understood  geological  phenomena.  To 
these  categories  year  by  year  we  are  enabled,  by  the  results  of 
extended  and  careful  investigation,  to  refer  many  that  have 
been  obscure.  A  number  of  familiar  terms  for  ore  bodies  in 
mining  literature  fail  to  appear,  but  are  mentioned  in  the 
classifications  quoted  from  others.  (See  Appendix  I.)  Many 
of  these  refer  only  to  form,  and  geologically  considered  are  only 
convenient  admissions  of  ignorance  as  to  origin.  Some  other 
ore  bodies  whose  methods  of  origin  are  involved  in  the  processes 
of  regional  metamorphism  are  placed  by  themselves  further  on. 
The  explanations  of  them  are  as  yet  hypothetical.  A  few  com- 
ments on  the  scheme  may  now  be  added,  although  in  the  main 
it  explains  itself. 

1.06.07.  I.  The  writings  of  Lagorio,  Iddings,  Rosenbusch 
and  others,  regarding  the  development  of  rocks  from  fused 
magmas,  have  emphasized  the  fact  that  the  laws  of  solution  do 
not  fail  to  apply,  because  the  magmas  are  raised  to  very  ele- 
vated temperatures ;  and  that  they  hold  good  for  fused  rock 
precisely  as  for  heated  water  or  any  other  solvent.  Other  laws 
of  physical  chemistry  and  of  thermodynamics  have  also  been 
recognized  by  many  as  fundamental  to  the  true  understanding 
of  the  reactions,  but  the  subject  is  a  difficult  one,  and  our  knowl- 
edge is  as  yet  incomplete.  The  reactions  are  complex  and 
occur  at  such  elevated  temperatures  as  to  render  observation 
difficult.     The  magmas  known  in  Nature  are  of  endless  va- 


R.  Pumpelly,  Bull.  Geol  Soc.  Amer.,  II.,  p.  230. 


60  KEMP'S  ORE  DEPOSITS. 

riety,  and  involve  a  number  of  bases.  Just  which  portion  is 
solvent  and  which  is  dissolved  matter  may  not  always  be  clear, 
nor  do  we  certainly  know  the  actual  state  in  which  the  ele- 
ments exist  at  these  high  temperatures,  nor  the  influence  of 
electrical  currents  or  still  more  obscure  forces.  Nevertheless, 
we  do  know  that  as  the  magma  cools  from  a  perfectly  fluid 
condition  the  flrst  minerals  to  separate  are  those  which  first, 
under  the  diminishing  temperature  (and  perhaps  pressure) 
reach  a  state  of  saturation  and  must  therefore  crystallize.  If 
this  is  expressed  in  the  terms  of  thermodynamics,  we  may  say 
that  those  compounds  will  first  form  Avhich  liberate  the  most 
heat  in  crystallizing,  and  so  on  down  to  complete  solidification. 
Usually  the  order  is  that  described  in  paragraph  1.03,05,  but 
mass  action,  brought  about  by  the  superabundance  of  one  ele- 
ment or  another,  may  affect  the  order,  and  the  variability  of 
composition  shown  by  igneous  rocks  is  also  a  serious  factor. 

Students  of  rocks  have  very  generally  reached  the  conclusion 
that  a  great  parent  magma  which  stands  molten  for  long  pe- 
riods in  the  earth  will  break  up  into  different  component  or 
fractional  magmas  before  any  mineral  crystallizes.  The  frac- 
tional magmas  by  successive  eruptions  afford  various  different 
types  of  rocks  of  greatly  contrasted  composition.  The  process 
is  called  differentiation,  and  it  is  of  interest  in  this  connection 
as  showing  in  a  general  way  the  tendency  of  fused  rock  masses 
to  break  up  and  vary. 

All  the  above  theoretical  considerations  throw  light  on  the 
formation  of  the  igneous  ore  bodies. 

1.06.08.  The  first  ore  bodies  to  which  an  igneous  origin  was 
attributed  in  the  past  were  those  portions  of  a  basic  intru- 
sion, such  as  a  peridotite  or  a  gabbro,  which  were  so  enriched 
with  magnetite  as  to  become  an  ore.  The  magnetite  is  almost 
always  titan  if  erous  and  may  indeed  be  ilmenite.  The  classic 
occurrence  of  this  type  is  Taberg,^  in  Sweden,  where  a  great 
boss  of  basic  igneous  rock  1.5  kilometers  (1.2  miles)  long, 
0.5    kilometer  (0.4  mile)  broad  and  130  meters  (400  ft.)  high  is 

'  A.  Sjogren,  Ueber  das  Eisenerzvorkommen  von  Taberg  in  Smaland, 
Geol.  Foren.  in  Stockholm,  Forhandl,  III.,  42-62, 1876,  and  VI.,  1882:  Neues 
Jahrbuch,  1876,  434. 

A.  E.  Tornebohm,  Om  Taberg  i  Smaaland  och  ett  par  dermed  analoga 
jernmalmforekomster.  Idem,  V.  610-619,  1881.  Neues  Jahrbuch,  1882, 
II..  66 


CLASSIFICATION  OF  ORE  DEPOSITS.  61 

found  intruded  in  granite-gneiss,  with  its  long  axis  parallel  to 
the  foliation.  In  the  central  part  of  the  boss  is  found  the  ore, 
a  mixture  of  titaniferous  magnetite  and  olivine,  but  the  boss 
shades  from  ore,  outwardly,  by  the  increase  of  feldspar  to  the 
variety  of  gabbro,  called  hyperite  in  Sweden.  In  the  basic  core 
and  acidic  rim  the  boss  differs  from  most  intrusions,  because  the 
latter  shade  from  acidic  cores  to  basic  rims.  The  Cumberland 
ore,  Rhode  Island,  forms  a  boss  of  titaniferous  magnetite 
mingled  with  olivine  and  pyroxene»  It  is  much  like  that  of 
Taberg.  The  ore  of  Brazil  is  strongly  titaniferous,  but  occurs 
in  basic  rocks  with  nepheline,  and  much  the  same  is  true  of 
Alno,  Sweden,^  where  nepheline  syenite  is  the  geological  asso- 
ciate. In  the  Adirondacks,  and  in  Minnesota,  Quebec,  Wyo- 
ming and  Norway,  huge  masses  of  quite  pure  titaniferous 
magnetite  occur  in  anorthosite  gabbros.  As  a  peculiar  phase 
of  the  Cortlandt  series  of  gabbros  on  the  Hudson  River,  near 
Peekskill,  there  are  richly  aluminous,  but  feebly  titaniferous 
ores  which  C0E<3ist  of  spinel,  corundum  and  titaniferous  mag- 
netite. At  Routivara,  Sweden,^  practically  the  same  aggre- 
gate has  been  found. 

1.06.09.  In  addition  to  the  igneous  magnetites,  chromite 
has  been  met  by  Vogt  in  an  outcrop  of  unaltered  peridotite 
'within  the  Arctic  circle,  in  Norway,^  and  J.  H.  Pratt*  attri- 
butes the  same  method  of  origin  to  the  chromite  of  North 
Carolina,  although  hitherto  chromite  in  serpentine  has  usually 
been  considered  a  segregation  produced  during  the  weathering 
of  rocks  which  possess  chrome -bearing  silicates.  Corundum  is 
now  reco'gnized  in  a  few  places  as  a  result  of  crystallization 
from  fusion.  The  special  conditions  of  its  formation  will  be 
noted  below. 

LOG.  10.  Aside  from  the  metallic  oxides  just  cited,  certain 
great  deposits  of  metallic  sulphides,  and  especially  of  chalcopy- 
rite  and  nickel-bearing  pyrrhotite,  are  likewise  regarded  as  the 
products  of  crystallization  from  fusion.     Many  Norwegian  lo- 

^  A.  G.  Hogbom,  Ueber  das  Nephelinsyenitgebiet  auf  der  Insel  Alno. 
Geol.  Faren.  Forhandl,  XVII.,  100,  214, 1895,  Neues  Jahrhuch,  1896,  I.,  252. 

2  W.  Peterson,  Geol.  Foren.  Forhandl,  XV.,  45-54,  1893.  H.  Sjogren, 
Ibid.,  55,  140-143. 

'  J.  H.  L.  Vogt,  Zeitsch.  fur  prakt.  Geologic,  January,  1894,  p.  389. 

*  J.  H.  Pratt,  Engineering  and  Mining  Journal,  Dec.  10,  1898,  p.  696 
Trans.  Amer.  Inst.  Min.  Eng.  (issued  May,  1899). 


62  KEMP'S  ORE  DEPOSITS. 

calities  and  in  America  the  Gap  Mine,  Pa. ;  the  Sudbury 
mines,  Ont.,  are  of  this  type.  The  gold-bearing  pyrrhotites  of 
Eossland,  British  Columbia,  resemble  it,  but  have  also  been 
esteemed  replacements.  All  these  sulphides  are  found  in  the 
outer  portions  of  the  intrusions. 

1.06.11.  In  discussing  the  chemical  and  physical  processes 
which  have  led  to  the  production  of  the  igneous  types  of  ore 
bodies,  it  is  important  to  emphasize  their  position  with  regard  to 
the  mass  of  the  intrusion,  i.e.,  whether  in  the  center  or  at  some 
other  point  well  within  the  intrusion,  or  whether  in  the  outer 
portions  near  the  contacts.  Somewhat  different  processes  may 
be  invoked  in  explanation  according  to  these  several  relations. 

1.06.12.  The  titaniferous  magnetites  are  either  centrally 
placed  or  else  are  so  far  within  the  mass  as  to  show  no  relations 
to  its  borders.  They  are  also  merely  exceptional  and  local  en- 
richments of  the  magma  with  one  of  its  more  abundant  compo- 
nent bases,  and  with  a  particular  mineral,  which  is  among  the 
earliest  to  separate  in  the  process  of  crystallization,  and  which 
has  the  highest  specific  gravity  of  any  of  those  entering  into 
the  rock.  Morozewicz^  has  sought  by  artificial  experiments  to 
determine  the  laws  which  govern  its  separation,  but  he  finds 
them  complex.  The  experiments  indicated  that  mass  action 
played  a  prominent  part,  and  that  with  an  abundance  of  the  iron 
oxides  the  crystallization  of  the  magnetite  preceded  that  of 
the  ferromagnesian  silicates;  with  less  it  began  after  them. 
The  iron  oxides  enter  as  bases  into  so  many  rock -forming  min- 
erals that  enough  to  satisfy  the  ferromagnesian  group  is  obvi- 
ously necessary  before  large  amounts  of  magnetite  can  be  ex- 
pected. If,  therefore,  we  assume  a  magma  excessively  rich  in 
iron  together  with  much  magnesia,  but  low  in  lime,  alumina  and 
alkalies,  an  aggregate  of  magnetite,  olivine  and  some  pyroxene 
will  necessarily  result  on  crystallization,  as  at  Taberg  and 
Cumberland.  To  explain,  however,  the  central  position  of  this 
basic  portion  in  an  otherwise  more  acidic,  average  magma 
is  not  so  simple.  If  again  we  assume  a  magma  fairly  rich  in 
iron,  soda,  lime,  alumina,  and  silica,  but  lacking  magnesia,  it 
is  conceivable  that  magnetite  and  labradorite  will  result  as  in 
the  anorthosites.     The  concentration  of  the  magnetite  seems  to 

^  Josef  Morozewicz.  Experiinentelle  Untersuchungen  tiber  die  Bildung 
der  Minerale  im  Magma.     Tschermaks  Mittheilungen,  XVIII.,  84,  1898. 


CLASSIFICATION  OF  ORE  DEPOSITS.  63 

the  writer  best  explained  by  its  settling  in  the  still  molten  mass 
until  it  has  formed  considerable  aggregates.  When  once  these 
rich  aggregates  have  formed,  they  may  in  the  process  of  erup- 
tion or  intrusion  take  almost  any  place  in  the  resulting  rock.^ 
Physico-chemical  reactions  may,  however,  be  operative  of 
which  at  present  we  are  not  aware.  Vogt^  has  suggested 
that  when  magnetite  crystals  have  formed  in  the  still  molten 
magma  they  may  become  aggregated  by  their  magnetic  attrac- 
tions, but  the  mineral  loses  its  magnetism  even  at  a  temper- 
ature below  redness,  and  it  is  doubtful  if  this  property  could 
affect  the  result. 

1.06.13,  Chromite  appears  at  times  in  masses  well  within 
the  peridotite  or  serpentine  which  contains  it,  and  it  also  is  no- 
ticeably abundant  near  the  contact^  in  other  occurrences. 
Corundum  furnishes  a  close  parallel.  It  has  been  met  in  very 
great  quantity  in  Ontario,*  north  of  Lake  Ontario,  in  nephe- 
line-syenite,  favoring  certain  varieties  of  the  rock,  but  dis- 
tributed all  through  it.  In  North  Carolina^  it  favors  the  outer 
portions  of  the  peridotite  (dunite)  in  which  it  is  found.  Sap- 
phires of  gem  quality  have  been  found  in  Montana  in  a  basic 
dike  consisting  chiefly  of  biotite,  diopside  and  magnetite.  Some- 
secondary  products  from  unrecognizable  originals  are  also 
present.^ 

The  chemical  conditions  under  which  corundum  separates 
from  igneous  magmas  have  been  very  clearly  shown  by  Moroze- 
wicz.'^    Without  regard  to  the  percentage  of  silica  in  the  rock, 

'  J.  F,  Kemp,  "The  Titaniferous  Magnetites  of  the  Adirondacks,"  etc., 
XIX.  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey  (in  press). 

^  Dannelse  af  Jernmalmforekomster,  Kristiania,  1892,  Resume  in  Ger- 
man, p.  145.  Vogt  also  mentions  the  concentration  by  settling  which  is 
set  forth  above. 

'J.  H.  Pratt,  "The  Occurrence,  Origin  and  Chemical  Composition  of 
Chromite"  (abstract),  Engineemng  and  Mining  Journal.  Dec.  10.  1898,  p. 
696.  Trans.  Amer.  Inst.  Min.  Eng. ,  February,  1899,  New  York  meeting. 
Refers  especially  to  North  Carolina. 

*  W.  G.  Miller,  Report  of  the  Ontario  Bureau  of  Mines,  VII.,  207,  1898. 

'  J.  H.  Pratt,  "On  the  Origin  of  the  Corundum  Associated  with  the 
Peridotites  in  North  Carolina,"  Amer.  Jour.  Sci.,  July,  1898,  p.  49. 

'  L,  V.  Pirsson,  "  Corundum-bearing  Rock  from  Yogo  Gulch,  Montana," 
Amer.  Jour.  Sci.,  December,  1897,  p.  421. 

'  Jozef  Morozewicz,  Experimentelle  Untersuchungen  iiber  die  Bildung 
der  Minerale  im  Magma,  Tshermaks  Mittheilungen,  XVIII.,  30,  1898. 


64  KEMP'S  ORE  DEPOSITS. 

provided  that  it  lies  within  the  limits  met  in  natural  magmas, 
free  alumina  will  separate  as  corundum,  when  the  molecular 
ratio  of  the  alumina  to  the  other  bases  is  greater  than  unity, 

i.  e.,  -p,  ^  I  ^\  ^1  T)  / ,    greater  than  1.     In  this  case  spinel  may 

be  anticipated  as  an  associate.  When,  therefore,  corundum 
is  found  in  a  natural  igneous  rock  this  condition  must  have 
been  met  at  the  time  it  crystallized.  As  to  the  causes  which 
have  produced  the  concentration  at  the  borders,  the  dis- 
cussion is  the  same  as  that  given  under  the  next  topic. 

1.06.14.  The  deposits  of  nickeliferous  and  auriferous  pyr- 
rhotite  and  of  chalcopyrite,  which  are  found  in  the  rims  of 
basic  intrusions,  present,  so  far  as  mining  is  concerned,  much 
larger  developments  than  the  chromite  and  corundum  just  re- 
ferred to,  and  the  important  applications  of  nickel  in  armor- 
plate  have  led  to  careful  study  of  the  ores.  They  are  recognized 
by  most  observers  as  crystallizations  from  fusion, and  the  prob- 
lem arises  as  to  the  causes  which  have  brought  them  into  their 
present  position. 

That  individual  intrusions  vary  from  a  more  acidic  (or  sili- 
ceous) composition  at  the  center  to  a  more  basic  one  at  the  bor- 
ders is  well  established  by  observation  and  by  progressive 
analyses  in  a  number  of  instances.^ 

An  explanation  of  these  relations  has  been  sought  in  what  is 
known  as  Soret's  principle.^  It  was  proved  by  experiments  in 
1879  by  Soret,  a  French  chemist,  that  if  differences  of  tempera- 
ture are  induced  in  a  solution  of  common  salt  or  other  sub- 
stance in  water,  the  dissolved  material  will  become  relatively 
concentrated  in  those  portions  in  which  the  temperature  is  low- 
est. It  has  also  been  shown  that  this  would  follow  from  the 
laws  of  osmosis,  and  that  the  relative  degrees  of  concentration 

^  See  Lawson  and  Shutt,  on  a  diabase  dike  in  the  Rainy  Lake  Region, 
Proc.  Amer.  Assoc.  Adv.  Set.,  1889,  346;  Alfred  Harker  on  an  English 
gabbro,  Quarterly  Journal  of  the  Geological  Society,  1894,  326;  W.  S. 
Bay  ley  on  Minnesota  gabbros,  Journal  of  Geology,  III.,  824,  1895. 

^  The  bearing  of  this  explanation  of  magmatic  differentiations  in  igneous 
rocks  upon  these  nickeliferous  deposits  has  been  especially  set  forth  by 
J.  H.  L.  Vogt  of  Kristiania,  Norway,  in  the  Zeitschrift  fur  Prdktische 
Geologic,  I.,  125,  1893,  under  the  title  "Sulphidische  Ausscheidungen  von 
Nickel-sulphid-erzen,"  etc. .  Other  related  papers  appear  in  the  same,  I.  4 
and  257;  II.  41,  134  and  173. 


CLASSIFICATION  OF  ORE  DEPOSITS.  65 

would  be  to  one  another  inversely  as  the  absolute  temperatures 
(^.e.,  temperature  Centigrade  plus  273).  The  lower  the  tem- 
perature, therefore,  the  more  dissolved  material  would  collect 
in  such  chilled  portion.  If  nov/  we  consider  a  fused  rock 
magma  as  a  complex  solution  of  several  silicates,  oxides,  sul- 
phides and  one  or  two  rarer  compounds,  some  in  others,  and  if 
we  regard  as  the  least  soluble  those  that  crystallize  first  in  the 
process  of  cooling,  we  are  led  by  Soret's  principle  to  infer  that 
these  would  tend  to  become  concentrated  in  the  portions  first 
cooled,  and  that  in  such  portions  they  would  be  especially  abun- 
dant after  consolidation.  The  portions  of  an  igneous  intrusion 
that  are  first  cooled  are  obviously  those  next  the  wall  rock. 
The  minerals  which  crystallize  first  are,  as  set  forth  earlier 
under  1.03.05,  magnetite,  ilmenite,  apatite,  pyrite,  pyrrhotite, 
and  several  minor  ones. 

In  the  case  of  nickeliferous  pyrrhotite  the  ore  bodies  are 
especially  rich  along  or  near  the  contacts  of  gabbroic  and  dio- 
ritic  intrusions  with  their  walls,  and  the  paper  of  J.  H.  L. 
Vogt,  cited  in  the  footnote,  has  served  to  bring  out  some  ex- 
tremely interesting  facts.  The  geological  relations  are  more 
fully  set  forth  later  on  under  nickel  and  in  connection  with 
several  American  occurrences,  but  it  may  be  here  added  that 
away  from  the  outer  wall  the  ore  bodies  fade  (at  least  at  the 
Gap  Mine,  Pa.)  into  barren  gabbro,  by  a  fairly  gradual  tran- 
sition. In  these  respects  they  conform  quite  closely  to  condi- 
tions which  would  result  from  a  development  according  to 
Soret's  principle.  We  also  find  in  such  ore  bodies  much  the 
same  association  of  minerals,  wherever  they  are  mined. 
Pyrrhotite  is  in  greatest  amount  and  contains  the  nickel  and 
cobalt  replacing  a  portion  of  its  iron;  as  the  rarer  mineral 
pentlandite/  or  as  secondary  coatings  of  millerite  in  cracks. 
Chalcopyrite  is  invariably  present,  often  in  important  quan- 
tity. Vogt  has  sought  to  trace  out  some  constancy  in  the  rela- 
tive amounts  of  these  several  metals,  but  the  attempt  is  not 
specially  successful.     He  also  cites  in  connecti  on  with  a  dis- 

*  S.  L.  Penfield,  "Pentlandite f rom  Sudbury,  Ont.,"  etc.,  Amer.  Jour.  Sci., 
June,  1893,  493.  Pentlandite  is  a  sulphide  of  iron  and  nickel,  isometric, 
non-magnetic,  and  with  a  somewhat  varying  percentage  of  nickel,  which 
reaches  at  Sudbury  34.23.     The  general  formula  from  Penfield's  analysis 

is  (NiFe)S. 


66  KEMP'S  ORE  DEPOSITS. 

cussion  of  their  early  formation  and  combination  with  sulphur 
in  the  fused  magma,  the  laws  which  we  know  apply  in  the 
metallurgical  processes  involving  slags  and  mattes.^ 

1.06.15.  Admitting  that  the  bases  iron,  nickel  and  copper, 
along  with  others,  have  been  concentrated,  while  etill  in  the 
state  of  ions,^  at  the  borders  by  Soret's  principle,  or  by  some 
other  process,  perhaps  not  clearly  understood,  objection  has 
still  been  made  to  the  igneous  origin  of  sulphides,  because  it  is 
believed  that  the  conditions  in  a  fused  magma  are  oxidizing — 
as  witness  the  presence  of  the  several  metals  in  almost  all 
igneous  rocks  as  oxides — and  because  oxidizing  conditions  would 
be  inimical  to  the  production  of  sulphides.  When  sulphides 
form  in  a  furnace,  it  is  urged  that  the  fuel  creates  a  reducing 
action,  and  that,  otherwise,  sulphides  would  be  impossible.  The 
analogy  of  a  furnace  is  not  to  be  too  sharply  urged  in  objection, 
for  the  reason  that  no  blast  of  oxygen  is  blown  through  a 
magma,  so  as  to  create  of  itself  an  intense  oxidation.  The 
abundance,  moreover,  of  ferrous  oxide  in  basic  rocks  indicates 
that  the  oxidizing  conditions  are  not  marked.  Nevertheless, 
to  meet  the  objections  to  the  formation  of  sulphides  in  mag- 
mas, while  assuming  the  greater  basicity  of  the  outer  portions  of 
the  mass,  the  writer'  has  suggested  that  the  escape  of  sulphur- 
ous gases  through  the  still  molten  rock  along  the  contacts 
would  produce  sulphides  of  metals  already  there,  even  though 
the  general  conditions  in  the  magma  were  oxidizing.  In  the 
original  paper  the  reactions  involved  are  justified  on  the  basis 

'  As  is  well  known  the  common  metals  may  be  ranged  in  the  following 
order  ("Fournet's  Series")  according  to  their  decreasing  affinity  for  sul- 
phur, Cu,  Ni,  Co,  Fe,  Sn,  Zn,  Pb,  Ag,  Sb,  As,  see  Vogt,  Zeitsch.  fiir  prakt. 
Geologic,  I.  363.  In  their  bearings  on  geological  phenomena  these  metal- 
lurgical laws  were  discussed  many  years  ago  by  Leonhard  in  HiXttener- 
zeugnisse  und  andere  auf  KiXnstlichem  Wege  gebildete  Mineralien  als 
Stuzpunkte  geologisher  Hypothesen,  Stuttgart,  1858.  The  succession  is 
determined  by  the  laws  of  thermochemistry,  and  necessarily  the  sulphides 
R^ill  form  in  order  according  to  the  amounts  of  heat  developed  by  the 
reaction,  from  the  greatest  to  the  least. 

^  The  term  ion  is  employed  in  modern  chemistry  to  describe  those  par- 
tial molecules  that  are  held  in  an  incomplete  state  by  electrical  force. 
The  word  is  derived  from  the  Greek  for  "going"  or  "moving,"  and  was 
suggested  by  the  partial  molecules  that  are  in  transit  in  an  electroplating 
bath. 

«  J.  F.  Kemp,  The  Mineral  Industry  for  1895,  Vol.  IV.,  761-766. 


CLASSIFICATION  OF  ORE  DEPOSITS  67 

of  physical  chemistry,  and  the  process  conceived  is  analogous 
to  bessemerizing  a  hath  of  oxides  with  sulphur  vapor,  as  con- 
trasted with  the  usual  artificial  process  of  oxidizing  a  bath  of 
molten  sulphides  with  a  blast  of  air. 

G.  F.  Becker^  has  presented  a  strong  argument  against  the 
ability  of  Soret's  principle  to  accomplish  serious  results  in  ef- 
fecting a  differentiation  of  an  originally  homogeneous  fluid 
magma  into  others  of  different  compositions,  and  cites  in  sup- 
port of  his  argument  the  slowness  and  feebleness  of  molecular 
flow  and  diffusion  as  indicated  by  artiflcial  experiments  with 
soluble  salts.  The  viscosity  of  fused  rock  gives  additional 
force  to  the  objection.  .  He  therefore  attributes^  the  changes  to 
convection  currents,  which  would  be  inevitably  set  up  in  the 
mass  by  its  differences  of  temperature  and  which,  as  they 
passed  along  the  cold  surfaces  inclosing  the  molten  fluid,  would 
coat  them  with  the  earlier  and  less  mobile  crystallizations.^ 
This  process  of  "fractional  crystallization"  is  beyond  question 
a  most  important  suggestion,  and  it  may  obviate  some  of  the 
difficulties  that  have  hitherto  been  serious. 

1.06.16.  As  opposed  to  the  igneous  view  others  have  re- 
garded ores  of  this  type  as  contact  deposits,  brought  about  by 
solutions  circulating  along  the  outer  portions  of  the  intrusions, 
and  replacing  or  impregnating  the  gabbro,  more  or  less,  with 
ore.  The  conception  is  a  time-honored  one;  it  involves  nothing 
unreasonable,  and  has  the  support  of  some  of  our  ablest  inves- 
tigators, as  Emmons*  and  Posepny,^  but  the  objections  to  the 
igneous  conception,  it  is  fair  to  state,  were  not  based  on  obser- 
vations of  the  phenomena,  but  on  general  theoretical  considera- 
tions. 

'  G.  F.  Becker,  ''Some  Queries  c.n  Rock  Differentiation,"  Amer.  Jour. 
Sci.,  January,  1897,  21. 

^  G.  F.  Becker,  "Fractional  Crystallization  in  Rocks,"  Idem,  October, 
1897,  257. 

^  A  very  suggestive  paper  in  this  connection  and  one  that  has  important 
applications  to  the  Sudbury,  Ont. ,  ores,  is  the  following :  ' '  Segregation  in 
Ores  and  Mattes,"  by  David  H.  Browne,  School  of  Mines  Quarterly,  July, 
1895,  297-311. 

*  S.  F.  Emmons,  "Geological  Distribution. of  the  Useful  Metals  in  the 
United  States,"  Trans.  Amer.  Inst.  Min.  Eng.,  Chicago,  1893.  Reprint 
pp.  18-19. 

^  F.  Posepny,  "The  Genesis  of  Ore  Deposits,"  Idem.     Reprint  p.  194. 


68  KEMP'S  ORE  DEPOSITS. 

1.06.17.  Under  II.  1,  the  precipitating  agencies  are  men- 
tioned, which  are  the  chief  causes  in  the  chemical  reactions  of 
deposition,  and  these  run  through  all  the  subterranean  cavities 
as  well.  Their  general  application  is  esteemed  self-evident.  The 
large  part  played  by  organic  matter,  both  when  living  and 
when  dead  and  decaying,  is  notable.  Its  office,  even  in  precipi- 
tating the  gangue  minerals  in  surface  reactions,  we  are  just  be- 
ginning to  appreciate.  Siliceous  sinters  have  been  shown  by 
W.  H.  Weed  to  be  formed  in  the  hot  springs  of  the  Yel- 
lowstone Park  through  the  agency  of  algae,  and  A.  Rothpletz 
has  recently  proved  that  the  calcareous  oolites  around  the 
Great  Salt  Lake  are  referable  to  minute  organisms.  Many 
accumulations  of  iron  ores  have,  with  reason,  been  attributed 
to  the  same  agency;  but  for  this  metal  ordinary  and  common 
chemical  reactions  are  oftenest  applicable.  When  organic  mat- 
ter decays,  sulphurous  gases  are  one  of  the  commonest  products, 
and  likewise  one  of  the  most  vigorous  of  precipitants.  Thus, 
under  Example  24,  Paragraph  2.06.03,  when  speaking  of  the 
Wisconsin  zinc  and  lead  mines,  it  will  be  seen  that  such  an 
agency  from  decaying  seaweeds  has  been  cited  by  both  Whit- 
ney and  Chamberlin.  When  the  products  of  this  decomposi- 
tion become  imprisoned  in  the  rocks  as  oils  and  gases,  their  ac- 
tion is  unmistakably  important  and  is  especially  available  in 
limestones.  Organic  matter  is  a  powerful  reducing  agent  as 
well,  and  in  this  way  is  capable  of  bringing  down  metallic 
compounds.  The  silver-bearing  sandstones^  of  southern  Utah 
are  cases  in  point,  as  they  afford  plant  impressions  now  coated 
with  argentite.  The  purely  physical  agencies  cited  under  {d )' 
have  also  an  important  role. 

1.06.18.  Under  2(a)  the  uprising  solutions  may  be  di- 
veirted  by  porous  strata,  so  as  to  pass  through  them,  and  be 
subjected  to  precipitating  agents  of  one  kind  or  another.  Porous 
beds  furnish  the  simplest  kind  of  cavities,  and  starting  with  these 
the  scheme  is  developed  in  a  crescendo  to  the  most  complicated. 
The  purely  chemical  action  of  limestone  beds,  however,  seems 
at  times  to  come  into  play  and  to  cause  precipitation  along 
them.  Of  all  rocks  they  are  the  most  active  chemical  reagent. 
It  may  be  questioned  with  reason  as  to  whether  caves  or  cav- 
erns (4),  properly  so  called,  have  formed  a  resting-place  for 
ores  as  often  as  some   observers   have   supposed.      So    many 


CLASSIFICATION  OF  ORE  DEPOSITS.  69 

which  have  been  cited  as  such  may  with  greater  reason  be 
referred  to  shrunken  replacements  that  each  case  should  be 
clearly  proven. 

1.06.19.  Under  (5)  brecciated  beds,  whose  fragments  are 
coated  and  whose  interstices  are  filled  with  ore,  are,  with  great 
reason,  referred  to  the  collapse  from  the  removal  of  a. support- 
ing layer.  In  addition  to  the  illustration  cited, the  red  hematite 
deposits  of  Dade  and  Crawford  counties,  Missouri,  have  been 
thought  to  have  had  a  similar  origin.  Such  phenomena  are 
only  to  be  expected  in  regions  that  have  long  been  land. 
Cracks  at  the  bends  of  folds  may  have  occasioned,  in  cases, 
impregnations  and  disseminations,  even  when  their  character 
is  obscured.  The  cracks  need  be  but  small  and  numerous  to 
have  produced  far-reaching  results.  If  a  fault  fissure,  as  a 
possible  conduit  of  supply,  crosses  the  axis  of  the  fold,  the  nec- 
essary conditions  are  afforded  for  extended  horizontal  enrich- 
ment. Recent  explorations  with  the  diamond  drill  at  Mine  la 
Motte  seem  to  corroborate  such  an  hypothesis.  Should  the 
anticline  or  roll  afterward  sink  toward  the  horizontal,  a  very 
puzzling  deposit  might  originate.  Shear  zones  have  been  al- 
ready discussed  at  length  (1.02.03),  as  have  true  veins  and 
volcanic  necks  (see  also  2.09.20).  As  regards  contact  deposits, 
the  igneous  rock,  which  usually  forms  one  wall,  may  serve  two 
different  purposes.  It  may  act  merely  as  an  impervious  bar- 
rier which  directs  solutions  along  its  course,  or  serves  to  hold 
them,  either  because  it  is  itself  bent  into  a  basin -like  fold,  or 
because  it  forms  a  trough  with  a  dense  bed  dipping  in  an  op- 
posite direction.  Such  relations  occur  in  the  Marquette  and 
Gogebic  ranges  of  the  Lake  Superior  iron  region.  It  is  not 
apparent  that  in  these  cases  the  heat  of  the  igneous  rock  has  in 
any  degree  stimulated  circulations.  In  the  more  characteristic 
"contact  deposits"  the  igneous  rock  has  apparently  been  a  strong 
promoter  of  ore-bearing  solutions,  and  has  often  been  the  source 
of  the  metals  themselves.  This  form  of  deposit  becomes,  then, 
an  attendant  phenomenon,  or  even  a  variety,  of  contact  meta- 
morphism. 

The  classic  illustration  of  it  is  furnished  by  the  deposits  of 
tin  ore  which  have  been  especially  developed  along  the  con- 
tacts of  granite  intrusions.  Granite,  as  is  well-known,  is  the 
most  potent  of  all  rocks  in  bringing  about  contact  metamor- 


70  KEMP'S  ORE  DEPOSITS. 

phism.  It  seems  to  be  especially  rich  in  mineral izers,  and  as  its 
great,  intruded,  batholitic  masses  slowly  crystallize,  they  emit 
boracic,  hydrofluoric  and  other  vapors  in  exceptional  volume. 
Wall  rocks  are  greatly  corroded  and  charged  with  tourmaline, 
fluorite,  axinite,  topaz,  fluoric  micas  and  cassiterite.  Peg- 
matite dikes  or  veins  are  sent  off  as  apophyses,  and  are  charged 
with  the  same  association  of  minerals.  If  the  walls  are  them- 
selves granitic  in  composition,  the  feldspar  becomes  greatly 
corroded,  and  may  be  replaced  by  quartz  and  fluoric  micas  with 
more  or  less  cassiterite.  Pegmatites  consisting  essentially  of 
the  same  minerals  are  also  produced,  and  both  varieties  are 
called  greisen,  and  are  recognized  as  the  characteristic  gangue 
of  tin  ores  the  world  over.  The  clue  to  the  formation  of  the 
cassiterite  in  these  surroundings  was  furnished  bj^  the  early 
experiments  of  Daubree,^  who  volatilized  the  bichloride  of  tin 
and  brought  it  into  contact  with  steam  in  a  tube,  obtaining  by 
double  decomposition  crystals  of  oxide  of  tin,  identical  in 
form  with  the  natural  ones.  In  Nature,  however,  the  fluoride 
of  tin  is  the  more  probable  source.  The  processes  by  which 
minerals  and  ores  are  emitted  from  igneous  rocks,  in  the  form 
of  heated  vapors,  are  often  called  pneumatolitic ;  and  if  water 
also  plays  a  part,  pneumato-hj'datogenic. 

Under  11  chromite  is  the  chief  illustration.  The  mineral  is 
practically  limited  to  serpentinous  rocks,  and  is  distributed 
through  them  in  irregular  masses.  It  has  been  considered  to  be 
a  product  of  alteration. 

1.06.20.  III.  The  debris  that  results  from  the  weathering 
of  rock  masses  under  the  action  of  frost,  wind,  rain,  heat  and 
cold,  is  washed  along  by  the  drainage  system  of  a  district,  and 
the  w^ell-known  sorting  action  transpires,  which  is  so  impor- 
tant in  connection  with  the  formation  of  the  sedimentary  rocks. 
Minerals  of  great  specific  gravity  tend  to  concentrate  by  them- 
selves, while  lighter  materials  are  washed  farther  from  the 
starting  point,  and  settle  only  in  still  water.  Stream  bottoms 
supply  the  most  favorable  situations,  and  in  their  bars  are 
found  accumulations  of  the  heavier  minerals  which  are  in 
the  surrounding  rocks.  The  commonest  of  these  are  magnetite, 
garnet,  ilmenite,  wolframite,  zircon,  topaz,  spinel,  etc.,  and  with 
these,  in  some  regions,  native  gold,  platinum,  iridosmine,  etc.; 
*  Annales  des  Mines,  XVI.,  129. 


CLASSIFICATION  OF  ORE  DEPOSITS.  71 

in  other  places  cassiterite,  or  stream  tin,  as  described  under  tin. 
Even  an  extremely  rare  mineral,  such  as  monazite,  may  make  a 
sandbar  of  considerable  size.^  The  action  of  the  surf  or  smaller 
shore  waves  is  also  a  favorable  agent.  The  throw  of  the 
breaker  tends  to  cast  the  heavier  material  on  the  beach,  where 
its  greater  specific  gravity  may  hold  it  stationary.  The  heav- 
ier minerals  may  be  sorted  out  of  a  great  amount  of  beach 
sand.  Magnetite  sands,  which  have  accumulated  in  this  way, 
are  of  quite  wide  distribution,  and  at  present  are  of  some 
though  not  great  importance.  (Example  15.)  With  the  mag- 
netite are  found  grains  of  garnet,  hornblende,  augite,  etc.,  and 
often  ilmenite.  Gold  is  concentrated  in  the  same  way  along 
the  Pacific  by  the  wash  of  surf  against  gravel  cliffs.  In  aban- 
doned beaches  of  Lake  Bonneville,  near  Fish  Springs,  Tooele 
County,  Utah,  placers  of  rolled  bowlders  of  argentiferous  ga- 
lena have  been  worked. 

A  superficial  deposit  of  somewhat  different  origin  is  the  bed 
of  hematite  fragments  that  mantles  thie  flanks  of  Iron  Moun- 
tain, Missouri,  and  runs  underneath  the  Cam bro-Silurian.  sand- 
stones and  limestones.  This  seems  to  have  been  produced  by 
the  subaerial  decay  of  the  porphyry  which  formerly  inclosed 
the  ore.  The  heavier  specular  ore  has  thus  been  concentrated 
by  its  greater  specific  gravity  and  resistant  powers.^ 

1.06.21.  There  remain  a  few  of  great  importance,  but 
whose  geological  history  is  less  clearly  understood.  They  are 
nearly-  all  involved  in  processes  of  regional  metamorphism,  and 
therefore  in  some  of  the  most  difficult  problems  of  the  science. 
Lenticular  beds  or  veins  of  magnetite  and  pyrite  that  are  inter- 
bedded  with  schists,  slates,  or  gneisses  are  the  principal  group. 
Such  magnetite  bodies  have  been  regarded  as  intruded  dikes, 
as  original  bodies  of  bog  ore  in  sediments,  which  have  later  be- 
come metamorphosed  ;  and  as  concentrated  delta,  river,  or  beach 
magnetite  sands.  It  is  possible  that  in  instances  they  may  be 
replaced  bodies  of  limestone,  afterward  metamorphosed.  The 
lenticular  shape  and  the  frequent  overlapping  arrangement  of 
the  feathering  edges  in  the  foot  wall  are  striking  phenomena. 

The  overlap  was  referred  by  H.   S.  Munroe,   in  the  School 

^  See  O.  A.  Derby,  Amer.  Jour.  Sci.,  III.,  xxxvii.,  p.  103. 
^  See  R.  Pumpelly,  "The  Secular  Disintegration  of  Rocks,"  Proc.  Oeol. 
Soc.  Amer.,  Vol.  II.,  December,  1890. 


72  KEMP'S  ORE  DEPOSITS. 

of  Mines  Quarterly,  Vol.  III.,  p.  34,  to  stream  action  during 
mechanical  deposition,  and  a  figure  of  some  hematite  lenses  in 
the  Marquette  region  was  given  in  illustration.  The  arrange- 
ment in  instances  also  suggests  the  shearing  and  buckling  pro- 
cesses of  dynamic  metamorphism  and  disturbance.  The  individ- 
ual lenses,  now  in  linear  series,  were  thus  all  one  original  bed. 
The  crumpling  of  the  schistose  rocks  has  pinched  them  by 
small  buckling  folds  and  shoved  the  ends  slightly  past  each 
other  in  the  process  so  familiar  in  the  production  of  reversed 
faults  from  monoclines.  Sheared  granitic  veins  on  a  small 
scale  are  a  not  uncommon  thing  in  areas  of  schistose  rocks, 
such  as  Manhattan  Island,  in  the  city  limits  of  New  York,  and 
suggest  strongly  this  explanation.  Should  the  compression  not 
go  so  far  as  to  bring  rupture  of  the  bed,  but  only  a  thickening 
by  the  formation  of  a  sigmoid  fold,  it  would  occasion  an  en- 
larged cross  section,  as  has  been  suggested  by  B.  T.  Putnam^ 
for  the  great  magnetite  ore  body  at  Mine  21,  Mineville,  in  the 
Lake  Champlain  region. 

1.06.22.  Quartz  veins,  often  auriferous  and  of  a  lenticular 
character,  furnish  another  puzzling  ore  body.  They  are  com- 
monly called  segregated  veins,  and  lie  interfoliated  in  slates  or 
schistose  rocks.  If  in  a  pre-existing  cavity,  the  cavity  must 
have  been  formed,  either  by  the  opening  of  beds  under  compres- 
sion, or  by  displacement  along  the  bedding,  so  that  depressions 
came  opposite  each  other.  Replaced  lenses  of  limestone  which 
had  been  squeezed  into  this  shape  from  an  original, connected  bed 
should  also  be  instanced  as  a  possibility.  But  notwithstanding 
the  time-honored  nature  of  the  conception  of  these  "segregated" 
veins,  there  is  little  doubt  that  they  are  practically  all  mere 
varieties  of  fissure  veins,  which  have  been  pinched  into  the 
separated  lenses  by  pressure, 

1.06.23.  The  veins  that  contain  cassiterite  in  many  parts  of 
the  world,  and  that  yet  have  the  mineralogical  composition  of 
granite,  are  another  product  of  metamorphic  action,  both  con- 
tact and  regional.  The  gangue  minerals,  feldspar,  quartz, 
and  mica,  are  quite  characteristic  of  acid,  igneous  rocks,  bui. 
the  coarseness  of  the  crystallization  in  the  comparativel}'  nar- 
row veins  bars  out  a  normal  igneous  form  of  origin.  All  our 
artificial   methods  of   reproducing    these  minerals   lead  us  to 

'  Tenth  Census,  Vol.  XV..  110. 


CLASSIFICATION  OF  ORE  DEPOSITS.  73 

infer  that  the  veins  were  filled  at  a  high  temperature  and  pres- 
sure, therefore  at  considerable  depths,  and  through  the  aid  of 
steam.  Cassiterite  has  also  been  detected  in  a  few  rare  cases, 
under  such  circumstances  that  it  seemed  to  be  an  original  min- 
eral in  igneous  granite.  It  is  probable,  therefore,  that  it  may 
in  instances  be  an  original  and  early  crystallization  from  an 
igneous  magma,  much  as  is  magnetite.  More  observed  cases 
would  be  welcome  as  evidence. 

1.06.24.  Fahlbands  should  be  mentioned  here.  The  term 
refers  to  belts  of  schists,  which  are  impregnated  with  sulphides, 
but  not  in  sufficient  amount  in  the  locality  where  the  name  was 
first  applied  (Kongsberg,  Norway)  to  be  available  for  ores. 
The  decomposition  of  the  sulphides  gave  the  schists  a  rusty  or 
rotten  appearance  that  suggested  the  name.  Whether  the  ores 
are  an  introduction  into  the  schist,  subsequent  to  metamorphism, 
or  a  deposit  in  and  with  the  original  sediment,  is  a  doubtful 
point.  The  practical  importance  of  these  fahlbands  lies  in  the 
enriching  influence  that  they  exert  on  the  small  fissure  veins 
that  cross  them. 

1.06.25.  The  phraseology  of  the  above  schemes  will  be  em- 
ployed in  the  subsequent  descriptions.  In  addition,  much  em- 
phasis will  be  placed  on  the  character  of  the  rocks  containing 
the  deposits,  whether  unaltered  sedimentary,  igneous,  or  meta- 
morphic,  and  whether  in  the  first  and  last  cases  igneous  rocks 
are  near,  for  these  considerations  enter  most  largely  into  ques- 
tions of  origin.  The  ore  deposits  are  illustrated  by  examples, 
somewhat  as  has  been  done  by  one  of  the  best  of  modern  writers 
abroad.  Von  Groddeck.  The  word  "example"  is  preferred  to 
"type,"  which  was  employed  by  Von  Groddeck,  because  it  im- 
plies less  of  an  individual  character.  We  may  cite  deposits 
under  different  metals  thus  which  all  might  belong  to  one  type. 
Under  each  metal  will  be  given,  first,  a  list  of  general  treatises 
and  papers.  These  will  be  marked  "Hist."  when  especially 
valuable  as  history,  and  "Rec."  when  recommended  for  ordi- 
nary examination.  If  not  marked  by  either,  they  are  more 
adapted  for  special  investigations. 


74  KEMP'S  ORE  DEPOSITS. 


GENERAL  REFERENCES  ON  ORE  DEPOSITS. 

Adams,  F.  D.  *'0n  the  Igneous  Origin  of  Certain  Ore  Depos- 
its, ' '  General  Mining  Association  of  the  Province  oj 
Quebec,  January,  1894. 

Ansted,  D.  T.  ''On  Some  Remarkable  Quartz  Veins,"  Quar. 
Jour.  Geol.  Sci.,  XIII.,  246. 

Barus,  Carl.  "The  Electrical  Activity  of  Ore  Bodies,"  Trans. 
Arner.  Inst.  Min.  Eng.,  XIII.,  417.  (See  also  Becker's 
Monograph  on  the  Comstock  Lode,  p.  310,  for  refer- 
ences to  other  papers. ) 

Becker,  G.  F.  "The  Relations  of  the  Mineral  Belts  of  the  Pa- 
cific Slope  to  the  Great  Upheavals,"  Amer.  Jour.  Sci., 
III.,  28,  209,   1884. 

Belt,  Th.  "Mineral  Veins;  an  Inquiry  into  their  Origin, 
founded  on  a  Study  of  the  Auriferous  Quartz  Veins  of 
Australia,"  London,  1861. 

Bischof,  G.  "On  the  Origin  of  Quartz  and  Metalliferous 
Veins,"  Jameson's  Journal,  April,  1845,  p.  344.  Ab- 
stract, Anfier.  Jour.  Sci.,  I.,  49,  396.  Advocates  aque- 
ous deposition. 

Brown,  A..  J.  "Formation  of  Fissures  and  the  Origin  of  their 
Mineral  Contents,"  Trans.  Amer.  Inst.  Min.  Eng.,  II., 
215. 

Bulkley,  F.  G.  "The  Separation  of  Strata  in  Folding,"  Idem, 
XIIL,  384. 

Campbell,  A.  C.  "Ore  Deposits,"  Engineering  and  Mining 
Journal,  July  17,  1880,  p.  39. 

Cotta-Prime  von.  "Ore  Deposits."  German,  by  Von  Cotta, 
1859;    English  translation  by  Prime,  1870.     Rec. 

Crosby,  W.  O.  "A  Classification  of  Economic  Geological  De- 
posits based  on  Origin  and  Original  Structure,"  Amer. 
Geologist,  April,  1894,  p.  249.     Rec. 

Cumenge,  E.,  et  Robellaz,  F.  L'Or  dans  la  Nature.  Paris, 
1898.     (Being  issued  in  parts,  1899.) 

Daubree,  G.  A.  Etudes  synthetiques  de  Geologic  experimentale. 
Paris,  1879. 


CLASSIFICATION  OF  ORE  DEPOSITS.  75 

Daiibree,    G.    A.      Les     Eaux    souterraines     aux     Epoques 

anciennes.     Paris,  1887. 
Les    Eaux    souterraines     a    I'Epoque    actuelle.     2    vols. 

Paris,  1887. 
De  Launay,  L.     Contribution  a  I'Etude  des  Gites  Metallif^res, 

Annates  des  Mines,  August,  1897. 
ErQmons,  E.     American  Geology,   134,   1853.     General    dis- 
cussion. 
Emmons,  S.  F.     **The  Structural  Relations  of  Ore  Deposits," 

Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  304.     Rec.        , 
"Notes  on  Some  Colorado   Ore  Deposits,"   Proc.    Colo. 

Sci.  Soc.,  II.,  Part  II.,  p.  35. 
"On  the  Origin  of  Fissure    Veins,"     Proc.     Colo.   Sci. 

Soc,  II.,  p.  189.     Rec.     (See  also  R.  C.  Hills,   Idem, 

III.,  p.  177.) 
"The  Genesis  of  Certain  Ore   Deposits,"   Trans.  Amer. 

Inst.  Min.  Eng.,  XV.,  125.  Rec. 
"Geological  Distribution  of  the  Useful    Metals    in    the 

United  States,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXII., 

52.     Rec. 
Endlich,  F.  M.     Hayden's  Survey,  1873,  p.  276.    General  de- 
scription of  veins. 
Fairbanks,  H.  W.     "The  Relation  between  Ore  Deposits  and 

their   Enclosing    Walls,"    Engineering   and  Mining 

Journal,  March  4,  1893,  p.  200. 
Foster,  C.  L.     "What  is  a  Mineral  Vein?"  Abstract  in  Oeol. 

Mag.,  Vol.  I.,  513. 
Fuchs,  E.,  et  De  Launay,  L.     Traite  des  Gites  Mineraux  et 

Metalliferes.     Paris,  1893.     Rec. 
Fox,  R.  W.     "Formation    of    Metallic    Veins    by    Galvanic 

Agency,"  Amer.  Jour.  Sci.,  I.,  37,  199.    Abstract  from 

London  and  Edinburgh  Phil.  Mag.,  January,  1839. 
"On  the  Electro-Magnetic     Properties    of    Metalliferous 

Veins  in  the  Mines  of  Cornwall,"  Amer.  Jour.  Sci.,  I., 

20,  136.     Abstract  of  paper  before  the  Royal  Society. 
Glenn,  W.     "The  Form  of  Fissure  Walls,  as  Affected  by  Sub- 

Fissuring  and  by  the  Flow  of  Rocks,"   Trans.  Amer, 

Inst.  Min.  Eng.,  XXV.,  499,  1895. 
Grimm,   J.     "Die  Lagerstatten  der  Nutzbaren  Mineralien," 

1869. 


76  KEMP'S  ORE  DEPOSITS. 

Groddeck,    A.    von.    *'The    Classification   of  Ore  Deposits,'^ 

Engineering  and  Mining  Journal,   June  27,  1885,  p. 

437. 
**Die  Lehre  von  den  Lagerstatten  der  Erze,"  1879.  Rec. 

(See  also,  Engineering  and  Mining  Journal,  Jan.  3^ 

1880,  p.  2,  for  a  review  of  same.) 
Hague,  A.  D.     "Mining  Industries,  Paris  Exposition,  1878.'* 
Henrich,  C.     **0n  Faults,"  Engineering  and  Mining  Jour- 
nal, Aug.  24,  1889,  p.  158. 
Hunt,  T.  S.     '*The  Geognostical  History  of  the  Metals,  Trans. 

Amer.  Inst.  Min.  Eng.,  I.,  331. 
**The  Origin  of  Metalliferous  Deposits,"  in  Chemical  and 

Geological  Essays. 
"Contributions  to  the   Chemistry  of   Natural   Waters," 

Amer.  Jour.  Sic,  11. ,  39,  176. 
Julien,  A.  A.     "On  the  Part  Played  by  Humus  Acids  in  Ore 

Deposit,  Wall  Rock,  Gossan,"  etc.,  Proc.  Amer.  Assoc. 

Adv.  Sic,  1879,  pp.  382,  385. 
Keck,  R.     "The  Genesis  of  Ore  Deposits,"  Engineering  and 

Mining  Journal,  Jan.  6,  1883,  p.  3. 
"Review  of  Ore  Deposits  in  Various  Countries."    Denver, 

1892.      31  pages. 
Kemp,  J.  F.     "A  Brief  Review  of  the  Literature  on  Ore  De- 
posits," School  of  Mines  Quarterly,  X-,  54,  116,  326; 

XL,  359  ;  XIL,  219. 
"On  the  Filling  of  Mineral  Veins,"   School  of  Mines 

Quarterly,  October,  1891. 
"The  Classification  of  Ore  Deposits,"  School  of  Mines 

Quarterly,  November,  1892. 
"On  the  Precipitation  of  Metallic  Sulphides  by  Natural 

Gas,"  Engineering  and  Mining  Journal,  December, 

1890. 
"An  Outline  of  the  Views  Held  To-day  on  the  Origin  of 

Ores,"  The  Mineral  Industry,  IV.,  755,  1895. 
Kimball,   J.  P.     "Our  Mineral  Interests,"  Memoirs  of  the 

American  Bureau  of  Mines. 
Kleinschmidt,   J.  .L.      "Gedanken    ueber    Erzvorkommen, " 

Berg-  und  Huet.  Zeit.,  1887,  p.  413. 
Koehler,  G.     "Die  Storungen  der  Gange,   Flotze,  u.  Lager," 

Leipzig,    1886.     Translated  by  W.    B.    Phillips    under 


CLASSIFICATION  OF  ORE  DEPOSITS.  77 

title  of  "Irregularities  of  Lodes,  Veins  and  Beds," 
Engineering  and  Mining  Journal^  June  25,  1887,  p. 
454;  also  July  2,  p.  4. 

Leconte,  J.     "Mineral  Vein  Formation  in  Progress  at  Steam- 
boat Springs,  compared  with  the  same  at  Sulphur  Bank," 
Amer.  Jour.  Sci.,  III.,  25,  424. 
"Genesis  of    Metalliferous   Veins,"    Amer.    Jour.    Set., 
July,  1883.     See  other  references  under  "Mercury." 

Leconte,  J.,  and  Rising,  W.  B.  "The  Phenomena  of  Metalli- 
ferous Vein  Formation  now  in  Progress  at  Sulphur 
Bank,  Cal."     A77ier.  Jour.  Sci.,  July,  1882,  p.  23. 

Moreau,  George.  "Etude  Industrielle  des  Gites  Metalli- 
feres,"  Paris,  1894.  Rec. 

Miiller,  A.     Erzgange.     Basel,  1880. 

Munroe,  H.  S.  "List  of  Books  on  Mining,"  School  of 
Mines  Quarterly,  X.,  176. 

Necker.  "On  the  Sublimation  Theory,"  Proc.  Geol.  Soc.  of 
London,  Vol.  I.,  p.  392;  also  Ansted's  Treatise  on  Ge- 
ology, Vol.    II.,  p.  271.     Hist. 

Newberry,  J.  S.     "The  Origin  and  Classification  of  Ore  De- 
posits," School  of  Mines  Quarterly,   I.,  March,  1880; 
Engineering  and  Mining  Journal,  June  19  and  July 
23,     1880;    Proc.    Amer.     Assoc.    Adv.     Sci.,    Vol. 
XXXIL,  p.  243,  1883.     Rec. 
**The  Deposition  of  Ores,"  School  of  Mines  Quarterly, 
v.,  329, 1884;  Engineering  and  Mining  Journal,  July 
19,  1884. 
**Genesi8  of  Our  Iron  Ores,"  School  of  Mines  Quarterly, 
II.,  1,  1880;  Engineering  and  Mining  Journal,  April 
23,  1881.     See  also  under  "Iron." 
"Genesis  and  Distribution   of  Gold,"   School  of  Mines 
Quarterly,  III.,  1881;  Engineering  and  Mining  Jour- 
nal, Dec.  24  and  31,  1881.     Rec. 

Ochsenius,  Carl.  ** Metalliferous  Ore  Deposits,"  Geol.  Mag., 
L,  310.     Hist. 

Pearce,  Rich.  "On  Replacement  of  Walls,"  Chem.  News, 
March  3,  1865. 

Penrose,  R.  A.  F.  "The  Superficial  Alteration  of  Ore  Depos- 
its,"  Journal  of  Geology,  11. ,  288,  1894.     Rec. 


78  KEMP'S  ORE  DEPOSITS. 

Phillips,  J.  A.     **The  Rocks  of  the  Mining  District  of  Corn- 
wall   and  thoir   Relations  to  Metalliferous   Deposits," 
Quar.  Jour.  Geol  Soc,  XXXI.,  319. 
'*A     Contribution    to    the   History   of    Mineral  Veins," 

Quar.  Jour.  Geol.  Sac,  X^XV.,  390. 
** Connexion  of  Certain  Phenomena  with  the    Origin    of 

Mineral  Veins,"  Phila.  Mgazine,  December,  1871. 
'*Treatiseon  Ore  Deposits,"  London,  1884. 
Posepny,  F.     Archiv  fiir  praktische  Geologie,  I.  and  II. 

'*The  Genesis  of  Ore  Deposits,"  Trans.  Amer.  Inst.  Min. 
Eng.,  XXII.,  63.     Rec. 
Power,  F.  D.     "The  Classification  of  Valuable  Mineral  De- 
posits," Trans.  Australasian  Inst.  Min.  Eng.,  189^. 
Pumpelly,  R.     Johnson\s  Encycl.,  Vol.  VI.,  p.  22.     Rec. 
Raymond,  R.  W.     **What   is   a  Pipe    Vein?"     Engineering^ 
and  Mining  Journal,  Nov.  23,  1878,  p.  361. 
Translation  of   Lottner,    and  general  remarks  on    Classi- 
fication, Min.  Stat.  West  of  Rocky  Mountains,  1870, 
p.  447. 
Indicative  Plants,  Trans,  Amer.  Inst.  Min.  Eng.,  XV., 

645. 
*' Geographical  Distribution   of   Mining  Districts    in    the 
United  States,"  Idem,  I.,  p.  33. 
Rickard,  T.  A.      ** Vein-Walls,"    Trans.  Amer,  Inst,  Min. 

Eng.,  XXVI.,  193,  1896. 
Sandberger,  F.       "Untersuchungen    iiber    Erzgange,"    1882; 
** Theories  of  the  Formation  of  Mineral  Veins,"    Engi- 
neering and  Mining  Journal,  March  15,  22,  29,  1884, 
pp.  197,  212,  232. 
**Untersuchungen  an  den  Erzgangen  von  Pribram  in  Boh- 
men,"  Sitzungsber.  der  Wiirzhurger  Phys.  Med,  Ge- 
sellschaft,  1886. 
Neue  Beweise  fiir  die   Abstammung  der  Erze  aus  dem 
Nebengestein,  Idem,  1883. 
Stelzner,  A.  W.     "Die  Lateralsecretions-Theorie  und  ihre  Be- 
deutung  fiir  das   Pribramer  Ganggebiet,"   B.  and   H. 
Jahrhuch    der    K.    K,     Bergakademie    zu    Leoben, 
XXXVII. 
Tarr,  R   S.     "The  Economic  Geology  of  the  United  States," 
1894. 


CLASSIFICATION  OF  ORE  DEPOSITS.  79 

Vogt,  J.  H.  L.     *'Bildung  von  Ezlagerstatten  durch  Differen- 

tiationsprocesse   in  basischen  Eruptivmagmata, "  Zeit- 

schrift  f.  praktische  Geologie,  1893,  pp.  4,  143,  257. 

Rec. 

**Ueber  die   Kieslagerstatten   vom   Typus    Roros,"   etc., 

Idem,  1896,  pp.  41,  117,  173.  Rec. 
** The  Formation  of  Eruptive  Ore  Deposits,"  The  Min- 
eral Industry,  IV.,  1895,  pp.  743,  754.  Rec. 
*'Ueber  die  relative  Verbreitung  der  Elemente,  besonders 
der  Schwermetalle,  und  ueber  die  Concentration  der  fein 
vertheilten  Metallgehaltes  zu  Erzlagerstatten, "  Zeit- 
schrift  fur  prakt.  Geologie,  August,  1898,  to  January, 
1899,  and  later.     Rec. 

Wabner,  R.  "Ueber  die  Eintheilung  der  Minerallagerstatten 
nach  ihrer  Gestalt,  sowie  die  Anwendung  und  die  Be- 
niitzung  der  Worte,  Lager  und  Flotz,"  Berg-  und 
Huet  Zeit,,  Jan.  2,  1891,  p.  1. 

Wads  worth,  M.  E.     "The   Theories  of  Ore  Deposits,"  Proc. 
Boston  Soc.  Nat.  Hist.,  1884,  p.  197.     Rec. 
**The  Lateral  Secretion  Theorj^  of  Ore  Deposits,"  Engi- 
neering and  Mining  Journal,  May  17,  1884,  p.  364. 
"Classification  of  Ore  Deposits,"   Bep.   of  Mich.   State 
Geologist,  1891-92,  p.  144.     Rec. 

Whitney,  J.  D.     "Remarks  on  the  Changes  which  take  place 
in  the  Structure  and  Composition  of  Mineral  Veins  near 
the  Surface,"  Amer.  Jour.  Sci.,  ii.  .XX.,  53. 
"Metallic  Wealth  of  the  United  States,"  1854.     Rec. 

Whittlesey,  C.  "On  the  Origin  of  Mineral  Veins,"  Proc. 
Amer.  Assoc.  Adv.  Sci.,  XXV.,  213. 

Williams,  Albert.  "Popular  Fallacies  Regarding  the  Pre- 
cious Metal  Ore  Deposits,"  Fourth  Ann.  Bep,  Director- 
U.  S.  Geol  Survey,  pp.  257-278. 


PART  II. 

THE    ORE    DEPOSITS. 


CHAPTER  I. 

THE  IRON   SERIES    (iN   PART)— INTRODUCTORY    REMARKS   ON 
IRON   ORES — LIMONITE— SIDERITE. 

GENERAL   LITERATURE. 

Birkinbine,  J.  "Prominent  Sources  of  Iron  Ore  Supply," 
Trans.  Amer,  Inst,  Min.  Eng,,  XVII.,  715,  Statis- 
tical; Rec.  g 
"The  Production  of  Iron  Ores  in  Various  Parts  of  the 
World."  Sixteenth  Ann.  Rep.  Dir.  U.  S.  GeoL 
Survey.  Part  III.,  21.     Rec. 

Chester,  A.  H.  "On  the  Percentage  of  Iron  in  Certain  Ores," 
Trans.  Amer.  Inst.  Min.  Eng.,  IV.,  219. 

Dunnington,  F.  P.  "On  the  Formation  of  the  Deposits  of 
Oxides  of  Manganese,"  Amer.  Jour.  Sci,,  iii.,  XXXVI., 
175.     The  paper  treats  of  Iron  also. 

Hewitt,  A.  S.     "Iron  and  Labor,"  Trans.  Amer.  Inst.  Min. 
Eng.,  XVIII.     The  paper  contains  valuable  statistics. 
"A  Century  of  Metallurgy,"  Idem,  V.,  164. 

Hunt,  T.  S.  "The  Iron  Ores  of  the  United  States,"  Idem, 
XIX,  3. 

Kimball,  J.  P.  "Genesis  of  Iron  Ores  by  Isomorphous  and 
Pseudomorphous  Replacement  of  Limestone,"  Amer. 
Jour.  Sci.,  September,  1891,  p.  231.  Continued  in  Amer. 
Geologist,  December,  1891. 

Julien,    A.    A.     "The  Genesis  of  the  Crystalline  Iron  Ores," 
Trans.  Phil.  Acad.  Nat.  Sci.,  1882,  p.  335;  Engineer- 
ing and  Mining  Journal,  Feb.  2,  1884. 
"Origin  of  the  Crystalline  Iron  Ores,"    Trans.    N.    Y. 
Acad.  Sci.,  IL,  p.  6;  Amer.  Jour.  Sci.,  iii.  XXV.,  476. 

Lesley,  J.  P.  "The  Iron  Manufacturers'  Guide,"  1866.  Hist. 
Rec. 

Newberry,  J.  S.      International  Review,  November  and  De- 
cember, 1874. 
"Genesis  of  the  Ores  of  Iron,"  School  of  Mines  Quar- 


84 


KEMP'S  ORE  DEPOSITS. 


terly.   November,   1880.     Rec.     Amer,  Jour.  Sci.,  iii., 
XXI.,  80. 
** Genesis  of  the  Crystalline  Iron  Ores,"    Trans.   N.    F. 
Acad.  Sci.,  II.,  October,  1882.     Rec. 

Newton,  H.  "The  Ores  of  Iron:  Their  Distribution  with  Ref- 
erence to  Industrial  Centers, "  Trans.  Amer.  Inst.  Min, 
Eng.,  III.,  360. 

Pumpelly,  R.,  and  Others.  Tenth  Census,  Vol.  XV.,  1886,  es- 
pecially pp.  3-17.     Rec. 

Reyer,  E.  ''Geologie  des  Eisens,"  Oest.  Zeit.  f.  B.  und  H., 
1882,  Vol.  XXX.,  pp.  89,  109. 

Rogers,  W.  B.  "On  the  Origin  and  Accumulation  of  the  Pro- 
tocarbonate  of  Iron  in  the  Coal  Measures,"  Froc.  Bos- 
ton Soc.  Nat.  His.,  1856. 

Smock,  J.  C.  "On  the  Geological  Distribution  of  the  Ores  of 
Iron,"   Trans.  Amer.  Inst.  Min.  Eng.,  XII.,  130. 
"Iron    Mines    and    Iron   Ore    Districts    in  New  York," 
Bull.  N.  Y.  Sta'te  Museum,  June,  1889.     Rec. 

Swank,  J.  M.     Chapters  on  Iron  in  Mineral  Resources^  U,  S. 
Geol.  Survey,  since  1883. 
"History  of  the  Manufacture  of  Iron  in  All  Ages."    1891. 

Whitney,  J.  D.     "Metallic  Wealth  of  the  United    States," 
1854,  p.  425.     Hist. 
"On  the  Occurrence  of  Iron  in  the  Azoic   System,"  Proc. 
Amer.  Assoc.  Adv.  Sci.,  1855,  209;  Amer.  Jour.  Sci., 
ii.  XXIL,  38. 

Winchell,  N.  H.  and  H.  V.  "The  Iron  Ores  of  Minnesota," 
Bull.  No.  6,  Minn.  Geol.  Survey,  1891.  Part  IV. 
contains  an  exhaustive  review  of  methods  of  origin,  and 
Part  V.  a  very  complete  annotated  bibliography. 

Table  of  the  Iron  Ores,  Limonite,  Siderite,  Hematite,  Magnetite,  Pyrite, 


Limonite  (brown  hematite,  bog  ore),  SFegOg 
SHgO 

Siderite  (Spathic  ore,  clay-ironstone,  black- 
band)  FeCOg 

Hematite  (red  and  specular),  FegOg 

Magnetite,  FeO,  FegOg,  or  Fe804 

Pyrite,  FeSg 


Fe. 


59.89    14.4 


48.27 
70.0 
72.4 
46.7 


CO, 


37.92 


53.3 


THE  IRON  SERIES  {IN  PART).  85 

2.01.01.  No  one  of  the  iron  ores  ever  occurs  pure  in  large 
amounts.  Only  a  few  closely  approach  this  condition.  The 
largest  Quantity  of  rich  ore  as  yet  mined  in  the  United  States 
was  doubtless  obtained  from  the  Lovers'  Pit  opening,  oper- 
ated by  Witherbee,  Sherman  &  Co.,  on  Barton  Hill,  near 
Mineville,  N.  Y.  The  pit  yielded  40,000  tons  of  magnetite 
that  averaged  68.6%  Fe,  with  many  carloads  at  72%.  The 
micaceous  specular  of  the  Republic  mine,  Mich.,  is  said  to 
have  been  shipped  an  entire  season  at  69%.  The  Min- 
nesota mines,  near  Tower,  Minn.,  have  cleared  many 
cargoes  at  68  to  68.4%.  The  richest  are  the  magnetites 
and  specular  hematites,  and  many  mines  of  the  Lake  Cham- 
plain  district  have  produced  the  former,  and  Lake  Superior 
mines  the  latter,  at  63  to  65%,  or  even  more.  The  separated 
ores  in  the  Lake  Champlain  district  run  about  65%.  The 
unseparated  ores  have  much  less,  and  indeed  all  percentages 
from  50  to  65.  Thus  the  lump  ore  (shipped  as  mined)  from 
Chateaugay,  N.  Y.,  has  about  50%.  The  Cornwall  (Pa.) 
magnetite  holds  even  less.  The  Clinton  red  hematites  from 
New  York  afford  about  44%  in  the  furnace,  as  the  result  of 
long  experience.  The  limonites,  as  usually  mined,  produce 
from  40  to  50%.  The  crude  spathic  oies  are  the  lowest  of  all, 
and  in  the  variety  black-band  may  even  be  about  30%.  They 
are  easily  calcined,  however,  and  on  losing  their  carbonic  acid, 
moisture  and  bituminous  matter  the  percentage  of  iron  rises  a 
third  or  more.  A.  H.  Chester  found  in  1875,  as  the  result  of 
an  endeavor  to  determine  the  average  yield  of  certain  standard 
ores  in  the  furnace,  Lake  Superior  specular,  62.5%;  Lake 
Superior  limonite,  49.5%,  which  is  much  too  low  to  be  sala- 
ble to-day;  Rossie  (N.  Y.)  red  hematite,  54.5%;  Wayne 
County  (N.  Y.)  Clinton  ore,  40%. 

2.01.02.  The  common  impurities  in  iron  ores  are  the  com- 
mon elements  or  oxides  that  enter  most  largely  into  rocks,  and 
those  which  make  up  the  walls  of  the  deposit  are  usually  the 
ones  that  appear  most  abundantly  in  the  ore.  Silica  (Si02),  alu- 
mina (AI2O3),  lime  (CaO),  magnesia  (MgO),  titanium  oxide 
(Ti02),  carbonic  acid  (CO2),  and  water  (HgO)  appear  in  large 
amounts  and  determine  to  a  great  extent  the  character,  fluxing 
properties,  etc.,  of  the  ore.  With  these,  and  of  more  far-reach- 
ing influence,  are  smaller  amounts  of  sulphur  and  phosphorus. 


86  KEMP'S  ORE  DEPOSITS. 

The  last  two  and  titanium  chiefly  determine  the  character  of 
the  iron  which  is  yielded  in  the  furnace,  and  are  the  first  foreign 
ingredients  sought  by  analysis.  The  sulphur  is  present  in  pyrite. 
the  phosphorus  in  apatite.  As  is  well  known,  0. 1%"  of  phosphorus 
is  set  as  the  extreme  limit  for  Bessemer  pig  irons,  and  as  ores 
for  these  command  the  best  market,  they  are  eagerly  sought. 
To  obtain  the  allowable  limit  of  phosphorus  in  the  ore,  its  per- 
centage in  iron  is  divided  by  1000.  Thus  a  65.3%  ore  should 
not  have  over  0.065%  phosphorus  to  be  ranked  as  Bessemer.  If 
at  the  same  time,  with  sufficiently  low  phosphorus,  the  gangue 
in  highl3^  siliceous,  a  composition  desirable  for  Bessemer  prac- 
tice, ores  have  been  of  value,  although  of  comparatively  low 
grade,  and  remotely  situated.  For  Lake  Superior  ores  the 
buyers  insist  to-day  on  a  still  lower  Bessemer  limit,  and  do  not 
call  any  ore  over  0. 05%  phosphorus  a  strictly  Bessemer  ore.  The 
ore  is  required  to  be  low  enough  to  carry  the  phosphorus  in 
both  fuel  and  flux,  and  still  yield  a  pig  iron  of  not  over  0.1%  P. 
On  the  other  hand  a  moderate  amount  of  phosphorus  is  not 
onl.y  no  drawback  for  ordinary  foundry-  irons,  and  such  as  are 
subjected  to  tool  treatment,  but  is  a  prime  necessity.  Excessive 
amounts  are  desired  only  for  weak  but  very  fluid  irons  or  for 
the  basic  steel  process.  Considerations  like  these,  which  are 
rather  metallurgical  than  geological,  largely  determine  the 
availability  of  a  deposit,  and  to  some  extent  the  present  loca- 
tions of  the  mining  districts. 

2.01.03.  Iron  itself  is  one  of  the  most  abundant  and  widely 
disseminated  elements  entering  into  the  composition  of  the 
earth.  Several  writers  have  attempted  to  deduce  the  general 
composition  of  the  outer  portions  of  the  globe, ^  but  the  most 
reliable  computation  is  that  of  F.  W.  Clarke  in  Bulletin  78 
of  the  U.  S.  Geol.  Surv.,  pp.  34-43.  The  crust  to  a  depth  of 
ten  miles  below  sea- level  is  the  subject  of  the  estimate,  and  the 
air  and  ocean  are  included.  The  composition  of  the  solid  crust 
is  reached  by  averaging  analj'ses  of  igneous  and  crystalline 
rocks,  880  in  all;  321  from  the  United  States,  75  from  Europe, 
and  486  from  all  quarters.  Igneous  rocks,  being  the  ultimate 
source  of  the  others,  furnish  a  good  average.     The  final  result 

*  Compare  Alex.  Winchell,  Geological  Studies,  pp.  19-20,  and  Prest- 
wich's  Geology,  I.  p.  10 — both  of  which  were  quoted  in  the  first  edition  of 
this  work. 


THE  IRON  SERIES  {IN  PART).  87 

is  the  following, in  which  amounts  less  than  0.01%  are  omitted. 
The  total  is  100.  . 


0 

49.98 

Na 

....3.28 

P 

0.09 

Si 

25.30 

K........ 

,...2.23 

Mn..o.. 

0.07 

Al 

7.26 

H 

0.94 

S 

0.04 

Fe.,..,, 

5.08 

Ti 

,...„0.30 

Ba..„... 

0.03 

Ca 

3.51 

C„.. ...... 

.O..0.21 

N 

0.02 

Mg...., 

2.50 

CI.  Br. . . . 

....0.15 

Cr 

0.01 

From  this  it  is  seen  that  iron  is  much  the  most  abundant 
of  the  useful  metals,  and  that  its  common  impurities,  titanium, 
phosphorus  and  sulphur  are  all  present  in  appreciable  amounts. 

2.01.04.  A  general  comparison  of  tabulated  analyses  of 
igneous  rocks  (Roth's  Gesteinsanalysen  and  Allgemeine 
Geologie)  shows  that  granites  contain  0.0-7%  iron  oxides,  por- 
phyries 0.0-14%,  rhyolites,  0.0-8%,  diorites  and  diabases  4-16%, 
andesites  3-15%,  basalts  12-20%.  Limestones  invariably  have 
at  least  small  amounts,  and  at  times  very  considerable  percent- 
ages. Sandstones  are  often  low,  but  not  seldom  are  stained 
through  and  through.  The  metamorphic  rocks  offer  close 
analogies  to  the  igneous.  In  general  distribution  and  in  quan- 
tity, iron  leads  the  list  of  the  distinctively  metallic  elements. 
Its  peculiar  property  of  possessing  two  oxides,  of  different 
chemical  quantivalence,  assists  greatly  in  the  formation  of  ores 
and  the  general  circulation  of  the  metal.  This  is  set  forth 
under  the  following  examples : 

LIMONITE. 

2.01.05.  Example  1.  Bog  Ore, — Beds  of  limonite,  super- 
ficially formed  in  marshes,  swamps,  and  pools  of  standing 
water.  The  general  circulation  of  water  through  the  rocks 
enables  it  very  frequently  to  take  up  iron  in  solution.  Ferru- 
ginous minerals  are  among  the  first  and  easiest  that  fall  a  prey 
to  alteration.  Carbonic  acid  in  the  water  aids  in  dissolving  the 
iron,  which  thus,  in  waters  containing  an  excess  of  COjj,  passes 
into  solution  as  the  protocarbonate  FeCOa.  Organic  acids  may 
also  play  a  part.  The  alteration  of  pyrite  affords  sulphuric 
acid  and  ferrous  sulphate,  and  the  latter  enters  readily  into 
solution.  On  meeting  calcium  carbonate,  both  ferric  and  fer- 
rous sulphate  are  decomposed, yielding  in  the  first  case  calcium 
sulphate,  ferric  hydrate,  and  carbonic  acid;  in  the  second,  if 


88 


KEMP'S  ORE  DEPOSITS. 


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THE  IRON  SERIES  [IN  PART).  89 

air  is  absent,  ferrous  carbonate  and  calcium  sulphate,  but  on 
the  admission  of  air,  ferric  hydrate  soon  forms.  ^ 

2.01.06.  Bodies  of  limonite  that  become  exposed  to  a  reduc- 
ing action  from  the  favorable  presence  of  decaying  organic 
matter  likewise  furnish  the  protocarbonate.  In  general  it  may 
be  stated  that  free  oxygen  must  be  absent  or  present  only  in 
small  quantity  where  solution  takes  place.  Sooner  or  later  the 
ferruginous  (or  chalybeate)  waters  come  to  rest,  especiallj"  in 
swamps.  The  protosalt  is  exposed  to  the  evaporation  of  the 
excess  of  CO2,  that  held  it  in  solution,  and  also  to  the  action 
of  oxygen.  Two  molecules  of  carbonate,  together  with  one 
atom  of  oxygen  and  some  water,  break  up  into  CO2,  and  the  hy- 
drated  oxide  2  FcgOs,  3  H2O,  or  some  related  molecule.  The 
latter  forms  as  a  scum  and  then  sinks  to  the  bottom  and  accu- 
mulates in  cellular  masses.  The  sesquioxide  is  insoluble, 
and  as  against  ordinary  waters  free  from  reducing  agents 
it  remains  intact.  Deposits  of  mud  and  peat  forming  above 
may  cover  the  beds  with  a  protecting  layer.  Hardly  a  bog 
exists  which  does  not  show,  when  cut  in  cross  section,  the  bog 
ore  beneath.  Frequent  associates  of  the  ore  are  diatomaceous 
earth  and  shell  marl,  contributed  by  the  remains  of  organisms 
which  once  inhabited  the  waters.  At  times  excellent  impres- 
sions of  leaves  and  shells  are  preserved  in  the  ore.  Such  ore 
bodies  are  not  often  practicably  available  on  account  of  the  low 
percentage  in  iron,  due  to  the  abundance  of  sand  and  silt 
washed  in,  and  to  the  frequent  large  amounts  of  sulphur  and 
phosphorus  which  they  contain.  The  sulphur  is  present  in  pyrite 
and  the  phosphorus  in  vivianite,  sometimes  in  sufficient  quan- 
tity to  be  visible  as  at  Mullica  Hill,  N.  J.,  where  the  variety 
Mullicite  is  found.  In  certain  parts  of  the  country  bog 
deposits  have  been  utilized  and  under  peculiar  conditions 
others  msiy  yet  be. 

2.01.07.  In  eastern  North  Carolina  bog-ore  beds  are  fre- 
quent and  are  found  Ijang  just  below  the  grass  roots.  Scat- 
tered nodules  occur  in  the  overlying  soil,  which  are  succeeded 
by  a  bed  three  feet  or  less  in  thickness,  resting  on  sand.^ 

^  F.  P.  Dunnington,  Amer.  Jour.  Set,  iii.,  XXXVI.,  176.  Experiments 
10  and  11. 

•"  W.  C.  Kerr,  Geology  of  North  Caroliiia,  1875,  p.  218.  B.  Willis, 
Tenth  Census,  Vol.  XV.,  p.  302.  H.  B.  C.  Nitze,  Bull.  I..  N.  C.  Geol. 
Survey,  1893. 


90  KEMP'S  ORE  DEPOSITS. 

In  HalPs  Valley  and  Handcart  Gulch,  Park  County,  Colo., 
interesting  and  extensive  deposits  of  limonite  are  in  ac- 
tive process  of  formation.  The  iron  comes  from  neighboring 
great  beds  of  pyrite.^ 

Bog  ore  of  good  quality  has  recently  been  reported  from  the 
vicinity  of  Great  Falls,  Mont.^ 

At  Port  Townsend  Bay,  in  the  vicinity  of  Puget  Sound, 
and  at  the  Patton  mines,  near  Portland,  Ore.,  the  ores  are  of 
such  quality  as  to  be  available.^ 

Attention  has  been  lately  directed  to  the  great  deposits  of  bog 
ore  in  the  Three  Rivers  district  of  the  Province  of  Quebec  in 
Canada.  Three  Rivers  is  on  the  St.  Lawrence  about  midway 
between  Montreal  and  Quebec,  but  the  district  which  furnishes 
the  bog  ores  extends  from  northeast  of  Quebec  to  a  point  west 
of  Ottawa,  an  area  stated  by  Griffin  to  be  400  miles  long  by 
40  to  60  broad.  The  drainage  of  the  old  Archean  heights  of  the 
Laurentides,  the  range  that  suggested  the  name  Laurentian, 
crosses  the  belt,  and  being  more  or  less  laden  with  ferruginous 
solutions  it  deposits  the  ore  in  swamps,  streams  and  lakes, 
wherever  the  water  is  for  a  time  stationary  or  choked  with 
vegetation.  The  ore  beds  furnish  ideal  illustrations  of  bog-ore 
deposits  in  all  their  forms.  Beginning  as  a  light  film,  the  ore 
gradually  accumulates  on  the  bottom,  where  it  hardens  into 
thick  crusts.  These  are  exposed  to  the  sun  in  the  dry  season 
in  the  shallower  reaches,  and  become  very  hard  cakes.  Dur- 
ing the  succeeding  wet  season  they  are  buried  again  under 
more  ore,  or  sand  and  ore,  until  the  thickness  attained  is 
very  '  considerable.  The  ore  is  precipitated  also  in  running 
Avater,  and  has  been  obtained  from  ravines  in  goodly 
amount.  Even  in  the  pipes  used  at  the  furnace  at  Radnor 
Forges  for  conveying  the  necessary  water  supply  from 
the  neighboring  Riviere  au  Lard,  the  limonite  deposits. 
The  river  flows  from  the  swamp  called  Grand  Pie,  in 
the  midst  of  which  is  a  shallow  lake  called  Lac  a  la  Tortue. 
Ore    is  dug   in  the  swamp  and  dredged  in  the   lake.      The 

*  R.  Chauvenet,  "  The  Iron  Resources  of  Colorado."  Trans.  Amer.  Inst. 
Min.  Eng.,  XVIII.,  266.  "Notes  on  Iron  Prospects  in  Northern  Coio 
rado,"  Ann.  Rep.  Colo.  School  of  Mines,  1886. 

^  Mineral  Resources,  U.  S.  Geol.  Survey,  1888,  p.  34. 

3  B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  496. 


THE  IRON  SERIES  {IN  PART), 


91 


rsupply  is  renewed  after  being  removed.  The  deposits  present 
many  analogies  with  those  of  the  Swedish  lakes,  later  men- 
tioned, but  they  supply  caked  ore  rather  than  the  oolitic  form 
of  the  latter.  The  iron  industry  began  in  the  region  in  1730  and 
has  continued  more  or  less  intermittently  to  date/  The  iron 
furnished  has  especial  excellence  for  car-wheels  and  chilled 
castings.  The  lake  ores  seem  to  run  somewhat  richer  than  those 
of  the  bogs.  The  latter  contain  about  42. 5%  Fe,  the  former  49%. 
Both  have  a  little  over  0.3%  P  and  less  than  0.1%  S.  These 
ore  bodies  are  of  great  scientific  interest,  for  they  illustrate  (as 
has  been  recognized  for  many  years)  the  formation  of  bodies  of 
other  kinds  of  iron  ores  when  in  sedimentary  series,  and  even 
when  metamorphosed. 


Ore  6-15 


Fig.  8. — Cross-section  of  the  Prosser  iron  mine,   near  Portland,   Ore., 

shoiving  the  bed  of  limonite  between  two  sheets  of  basalt.    After 

B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  496. 

2.01.08.  A  somewhat  different  variety  of  Example  1  results 
when  the  ferruginous  waters  come  to  rest  in  the  superficial  hol- 
lows of  the  rock  which  has  furnished  the  iron.  Depressions 
in  the  serpentines  of  Staten  Island,  N.  Y.,  contain  such  deposits, 
and  the  ore  has  been  referred  by  N.  L.  Britton  to  the  leaching 
of  the  underlying  rock.  It  contains  a  notable  percentage  of 
chromium,  which  is  known  to  be  an  element  in  the  serpentine. 
The  mines  have  been  in  former  years  quite  large  producers. 
Similar  limonites  occur  at  Rye,  N.  Y.^ 

'  See  especially,  P.  H.  Griffin,  "  The  Manufacture  of  Charcoal-iron  from 
the  Bog  and  Lake-ores  of  the  Three  Rivers  District,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XXI.,  974.  Also  J.  H.  Bartlett,  Trans.  Amer.  Inst.  Min. 
Eng.,   XIV.,  508.  ^  j^-.  l.  Britton,  School  of  Mines  Quarterly,  May, 

1881.     Compare  also  Amer.  Jour.  Sci.,  iii.,  XX.,  32,  and  XXII.,  488. 


92  KEMP'S  ORE  DEPOSITS. 

At  the  Prosser  mines,  Dear  Portland,  Ore.,  deposits  of  limo- 
nite  are  found  in  the  superficial  hollows  of  a  Tertiary  basalt  of 
the  Cascade  range.  The  ore  contains  roots  and  trunks  of  trees, 
and  is  coveied  by  a  later  flow  of  basalt.  Similar  bodies  of 
limonite  resulting  from  basalt  are  known  in  the  German  prov- 
ince of  Hesse,  and  in  Ireland.^ 

2.01.09.  The  limonite  sand,  or  oolite,  that  forms  in  the 
Swedish  lakes  about  ten  meters  from  the  banks  and  in  water  up 
to  ten  meters  in  depth  is  another  variety  of  this  type.  A  layer 
half  a  meter  and  less  in  thickness  accumulates  every  fifteen  to 
thirty  years,  and  is  periodically  dredged  out.  The  ore  is  precipi- 
tated first  as  a  slime  that  breaks  up  afterward  into  small  con- 
cretions. It  has  been  thought  that  the  formation  of  these  and 
similar  bodies  of  limonite  has  been  aided  by  small  algse  and 
other  plants  or  microscopic  organisms.^ 

2.01.10.  Example  2.  Bodies  of  limonite  in  cavities  of  fer- 
ruginous rocks,  on  the  outcrop,  or  below  the  surface,  which 
have  resulted  either  from  the  alteration  of  the  rock  in  situ  or 
from  its  partial  replacement  by  limonite.  Residual  clay, 
quartz  and  other  remains  of  alteration  usually  occur  with  the 
ore.  Ferruginous  limestones  are  the  commonest  sources  of 
such  deposits,  but  other  rocks  may  afford  them.  The  deposits 
are  not  limited  to  any  one  geological  series,  but  in  different 
parts  of  the  country  occur  wherever  the  conditions  have  been 
favorable.  Some  of  the  ore  may  have  been  brought  in  by  sub- 
terranean circulations  which  have  leached  the  neighboring 
rocks.  Considerable  limonite  has  also  resulted  from  the  weath- 
ering of  clay- ironstone  nodules   and    black-band  beds  in  the 

'  B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  16,  and  J.  S.  Diller,  "A 
Geological  Reconnaissance  in  Northwestern  Oregon,"  Eighteenth  Ann. 
Rep.  U.  S.  Geol.  Survey,  Part  II. ,  on  the  Oregon  ore ;  Tasche,  Berg.  -  und 
Hutt.  Zeit.,  1886,  p.  209;  also  Wurtemberger,  Neues  Jahrh.,  1867,  p.  685, 
on  the  Hessian  ores;  Tate  and  Holden,  "On  the  Iron  Ores  Associated  with 
the  Basalt  of  Northeastern  Ireland,"  Quar.  Jour.  Geol.  Soc,  XXVI.,  151. 

^  F.  M.  Stapff,  Zeitschr.  d.  d.  geolog.  Gesellsch.,  1866,  Vol.  XVIII.,  p.  8, 
on  the  geology  of  the  ores.  Sjogrun,  Berg.-  und  Hutt.  Zeit.,  1865,  p.  116, 
on  the  agency  of  algse.  On  the  general  formation  of  bog  ores  the  follow- 
ing papers  are  of  interest :  G.  J.  Brush  and  C.  S.  Rodman,  ' '  Observations 
on  the  Natives  Hydrates  of  Iron,"  Amer.  Jour.  Set.,  ii.,  XLIV.,  219;  J.  S. 
Newberry,  School  of  Mines  Quarterly,  November,  1880;  J.  Roth,  Chem. 
und  Phys.  Geologic,  I.,  pp.  58,  97,  221;  F.  Senft,  Humus,  Marsch,  Torf 
und  Limonit-bildungen. 


THE  IRON  SERIES  {IN  PART). 


93 


Carboniferous  system  (to  be  mentioned  later),  and  not  infre- 
quently from  the  alteration  of  nodular  masses  of  pyrites.  The 
limonite  is  in  cellular  lumps,  in  pipes,  pots,  and  various  imi- 
tative forms  which  often  have  a  beautiful  lustre.  The  hollow 
inasses  have  in  general  resulted  from  the  filling  of  reticulated 
cracks  in  shattered  rock.  The  ore  thus  deposits  around  the 
cores  of  country  rock,  which  afterward  are  removed,  leaving 
a  hollow  shell,  or  geode.  (See  Tenth  Census,  Vol.  XV.,  pp. 
275,  3G9,  370.) 


Fig.    9, — Section   of  the   Hurst  limonite  hank,    Wythe   County,    Virginia, 

illustrating  the  replacement  of  shattered  limestone  with  limonite 

and  the  formation  of  g codes  of  ore.     After  E.  R.  Benton, 

Tenth  Census,  Vol.  XV.,  p.  275. 


2.01.11.  Reserving  the  Siluro-Cambrian  limonitesfor  a  sub- 
type the  ore  bodies  are  described  in  order  from  east  to  west, 
taking  up  first  the  Allegheny  region,  then  the  Mississippi  Val- 
ley, and  lastly  the  Rocky  Mountains.  The  limonites  of  New 
England  and  New  York  belong  to  the  present  subtype,  as  do 
those  of  eastern  Pennsylvania  and  the  more  important  ones  in 
Virginia,  Tennessee,  Georgia  and  Alabama.  In  central  and 
western  Pennsylvania,  however,  not  a  small  amount  is  obtained 
from  the  higher  lying  terranes.  The  Hudson  River  slates  fur- 
nish small  amounts  in  Franklin  County,  which  are  thought  by 
McCreath  to  have  resulted  from  the  alteration  of  nodules  of 


94  KEMP'S  ORE  DEPOSITS. 

pyrites/  The  Medina  sandstones  contain  highly  ferruginous 
portions  in  Huntingdon  County.^  The  lower  Helderberg  and 
Oriskany  are  locally  quite  productive  in  Blair  County, 
affording  several  great  banks  of  ore/  The  Oriskany  is  of 
greater  importance  in  Virginia  than  in  Pennsylvania.  East 
of  these  last-mentioned  exposures,  and  in  southern  Carbon 
County,  in  a  bed  of  paint  ore  between  the  Oriskany  and  the 
Marcellus.*  The  Marcellus  is  the  most  productive  of  the 
Devonian  stages.  It  affords  considerable  ore  in  Perr}^  County,^ 
Juniata  County,  Mifflin  County,  Huntingdon  County/ 
Fulton  County^  and  Franklin  County/  All  these  are  in 
southern  Pennsylvania.  Lesley  states^  that  the  ore  is  weathered 
carbonate.  As  shown  under  Example  4,  beds  of  carbonate  ore 
occur  in  Ulster  County,  New  York,  in  the  Marcellus.  (Addi- 
tional details  on  the  above  Pennsylvania  deposits  will  be  found 
ill  the  geological  reports  on  the  particular  counties.) 

2.01.12.  As  already  remarked,  the  greater  part  of  the  limon- 
ites  in  Virginia  belong  under  the  Siluro-Cambrian  division 
and  are  there  described,  but  in  the  James  Eiver  Basin,  on  Pur- 
gatory and  May's  Mountains,  there  are  deposits  in  sandstones 
of  the  Clinton.^"  Other  limonite  beds  occur  in  the  Oriskany  on 
Brushy  Mountain  (Longdale  mines),  on  Rich  Patch  Mountain 
(Low  Moor  mines,  called  by  Lyman,  Marcellus),  on  Warm 
Spring  Mountain,  and  on  Peter  Mountain.  In  the  Shenandoah 
Valley,  on  Massanutton  Mountain,  the  limonite  is  referred 
by  Prime  to  the  Clinton  stage."  On  North  Mountain  it  lies  in 
the  Oriskany,  according  to  CampbelP^  and  on  the  Great  North 
Mountain  in  the   Upper   Silurian.    Considerable  oxide  of  zinc 

^  Second  Penn.  Geol.  Survey,  M3,  p.  x.  • 

^  McCreath,  Second  Penn.  Geol.  Survey,  MM,  p.  198. 

5  Report  MM,  196,  M8,  p.  33. 

*  C.  E.  Hesse,  "The  Paint-Ore  Mines  at  Lehigh  Gap,"    Trans.   Amen 
Inst.  Min.  Eng.  XIX.,  321. 

^  Report  MM,  p.  193;  M3,  p.  29. 

«  Report  M,  p.  66;  MM,  p.  194;  M3,  p.  140. 

'  Report  M3,  p.  42. 

«  Report  M3,  p.  1. 

•  Iron  Manufacturers'  Guide,  p.  650. 

"J.  L.  Campbell,  The  Virginias,  July,  1880 
"  The  Virginias,  March,  1880,  p.  35. 
^^  Ihid..  January,  1880,  p.  6. 


THE  IRON  SERIES  (IN  PART).  95 

collects  in  the  tunnel  heads  of  the  furnaces  running  on  Low 
Moor  ores,  indicating  the  presence  of  this  metal  in  the  limonite/ 

The  Oriskany  ores  (including  those  referred  by  Lyman  to 
the  Marcellus)  were  fornaerly  the  chief  sources  of  Virginia  iron, 
and  at  Longdate  and  Low  Moor  afforded  very  large  amounts, 
but  lately  the  Siluro- Cambrian  have  taken  precedence.  The 
Oriskany  ores  yield  from  40  to  43%  Fe  in  the  furnace  (Pechin), 
and  were  non-Bessemer.  They  have  an  excellent  reputation 
for  foundry  and  mill  work.  Another  prominent  source  of 
brown  hematite  ores  in  Virginia  has  been  of  recent  years  the 
weathered  and  oxidized  upper  portions  of  the  great  pyrites 
deposits  in  Floyd,  Grayson  and  Carroll  counties,  in  the  south- 
western part  of  the  State.  This  belt  extends  over  20  miles,  and 
is  known  as  the  "Great  Gossan  Lead."  Although  uniformly 
pyrites  or  pyrrhotite  below  the  water  line,  it  is  sufficiently  oxi- 
dized above  to  yield  an  ore  of  about  40  to  41%  Fe,  with  the 
sulphur  not  much  over  one  per  cent.  The  greatest  depth  is 
attained  where  the  belt  crossses  the  hills.  The  ores  supply  a 
useful  mixture  for  the  neighboring  Siluro- Cambrian  brown 
hematites. '^ 

The  iron  ores  in  Kentucky  are  found  in  three  widely  sepa- 
rated districts,  one  near  Greenup,  in  the  northeastern  corner  of 
the  State,  known  as  the  Hanging  Rock  region ;  the  second  near 
the  central  part  along  the  Red  and  Kentucky  rivers,  known  as 
the  Kentucky  and  Red  River  region;  and  the  third  in  the 
southwestern  part  near  Lyon  and  Trigg  Counties,  known  as 
the  Cumberland  River  region.  Although  the  first  two  contain 
much  limonite,  it  has  altered  from  nodules  of  carbonate,  and 
the  ores  are  therefore  described  under  Example  5.  One  locality 
near  Owingsville,  in  the  second  region,  has  limonites  altered 
from  the  Clinton  hematite.  (See  Example  6.)  The  Cumberland 
region  affords  limonites  in  the  Subcarboniferous.     They  are  in 

'  B.  S.  Lyman,  "  Geology  of  the  Low  Moor,  Va.,  Iron  Ores."  Trans. 
Amer.  Inst.  Min.  Eng.,  XIV.,  801.  E.  C.  Means,  "Flue  Dust  at  Low 
Moor,  Va.,"  Trans.  Amer.  Inst.  Mm.  Eng.,  XVII.,  129.  E.  C.  Pechin,  "  Vir- 
ginia Oriskany  Iron  Ores,"  Engineering  and  Mining  Journal,  August 
13,  1892,  p.  150;  "Oriskany  Iron  Ores  at  Rich  Patch  Mountain,"  Idem^ 
February  1,  8,  and  15,  1896;  "Iron  Ores  of  Virginia,"  etc.,  Trans.  Amer. 
Inst.  Min.  Eng.,  XIX.,  p.  1016,  1890. 

'^E.  C.  Moxham,  "The  Great  Gossan  Lead  of  Virginia,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XXL,  133,  1892. 


96 


KEMP'S  ORE  DEPOSITS, 


rounded  masses,  either  solid  or  hollow,  and  are  distributed 
through  a  red  clay  along  with  angular  fragments  of  chert.  The 
limonite  pots  are  themselves  filled  with  clay  or  water/ 

2.01.13.  In  Tennessee  the  limonites  of  the  eastern  portion 
come  mostly  under  Example  2a.  In  the  west  they  are  a  souths 
ern  extension  of  the  pot-ore  deposits  of  Kentucky,  and  show  the 
same  associated  chert  and  clay.  Safford  has  called  the  rocks 
containing  them  the  Siliceous  Group.  The  west  Tennessee  dis- 
trict projects  into  Alabama  to  a  small  extent.^ 

2.01.14.  The  principal  limonite  deposits  of  Alabama  come 
under  Example  2  a,  as  do  those  of  western  North  Carolina  and 
Georgia.     Some  limonite  is   produced  in  Ohio,  but  it  is  all 


Fig.  11. — Oeological  Section  of  the  Low  Moor,    Va.,   Iron-ore  Bed. 
B.  S.  Lyman,  Trans.  Amer.  List.  Min.  Eng.,  XIV.,  801.     A— 
Marcellus  Shale;  B — Oriskany  Sandstone;  C — Lower 
Helderherg  Limestone;  D — Clinton  Shales. 


After 


weathered  carbonate  and  is  mentioned  under  Example  5. 
Hydrated  ores  are  abundant  in  the  Lake  Superior  region,  but 
are  mentioned  in  connection  with  hematite.  (See  also  2.01.22.) 
Deposits  of  brown  hematite  are  worked  in  a  small  way  in  the 
southeastern  part  of  Missouri,  where  they  rest  upon  Cambrian 
strata  and  have  a  marked  stalactitic  character.^ 

Limonites  referred  to  the  Cretaceous  by  N.  H.  Winchell 
occur  in  western  Minnesota.* 

2.01.15.  The  Annual  Report  of  the  Geological  Survey  of 
Arkansas,  Vol.  I.,  consists  of  a  report  by  E.  A.  P.  Penrose 
on  the  "Iron  Deposits  of  Arkansas."  It  at  once  appears  that 
there   is   little  prospect  of  Arkansas  producing   any  notable 

*  W.  B.  Caldwell,  ' '  Report  on  the  Limonite  Ores  of  Trigg,  Lyon,  and 
Caldwell  Counties,"  Kentucky  Geol.  Survey,  New  Series,  Vol.  V.,  p.  251. 

3  W.  M.  Chauvenet,  Tenth  Census,  Vol.  XV.,  p.  357;  J.  H.  Safford,  Geol- 
ogy of  Tennessee,  p.  350. 

^  P.  N.  Moore,  Oeol.  Survey  of  Missouri,  Report  for  1874;  F.  L. 
Nason,  Mo.  Geol  Survey,  1892,  II.,  p.  158. 

*  Bull  VL,  Minn.  Geol.  Survey >  p.  151. 


THE  IRON  SERIES  {IN  PART).  97 

amounts  of  iron  ore.  Such  deposits  as  have  been  found  are 
practically  all  limonite  (brown  hematite)  and  are  generally 
very  low  in  iron.  The  ores  occur  in  five  districts,  viz. :  North- 
eastern Arkansas,  northwestern  Arkansas,  the  valley  of  the 
Arkansas  River,  the  Ouachita  Mountains,  and  southern  Arkan- 
sas. They  are  generally  associated  with  sandstones  or  cherty 
limestones.  The  first-named  district  makes  the  best  showing. 
In  it  the  ores  are  in  Lower  Silurian  (Calciferous  or  lower) 
sandstones,  cherts  and  limestones.  In  the  second  district  they 
are  in  Lower  Silurian  cherts,  and  Lower  Carboniferous  sand- 
stones. In  the  third  they  occur  with  Carboniferous  and  Lower 
Carboniferous  strata,  but  are  also  in  the  form  of  recent  spring 
deposits.  In  the  Ouachita  Mountains  they  are  with  Lower 
Silurian  shales  and  novaculites.  In  this  district  the  magne- 
tite or  natural  lodestone  of  Magnet  Cove  occurs,  but  it  is  only 
an  interesting  mineral,  and  of  no  practical  importance.  The 
last  district  has  the  ores  in  sands  and  clays  of  the  Eocene,  Its 
continuation  in  Texas  and  Louisiana  is  referred  to  below. 

In  eastern  Texas,  along  the  latitude  of  the  northern  boundary 
of  Louisiana,  extended  beds  of  limonite  are  found  capping  the 
mesas  or  near  their  tops,  and  associated  with  glauconitic  sands 
of  Tertiary  age.  They  are  described  by  Penrose^  as  (1)  brown 
laminated  ores,  (2)  nodular  or  geode  ores,  (3)  conglom 
€rate  ores.  The  first  form  extended  beds  whose  firmness 
has  prevented  the  erosion  of  the  hills,  and  which  are  thought 
to  have  originated  by  the  weathering  of  the  pyrites  in  the 
greensands  and  from  the  iron  of  the  glauconite  itself.  The 
second  group  occur  just  north  of  the  last,  and  have  probably 
resulted  from  the  alteration  of  clay  ironstone  nodules  (Cf, 
Example  5),  while  the  third  has  formed  in  the  streams  by  the 
erosion  of  the  first  two  and  from  the  smaller  ore-streaks  and 
segregations.  Limonite  also  occurs  in  northwestern  Louis- 
iana.^ Lawrence  C.  Johnson  has  also  written  of  these  ores,^ 
but  the  most  complete  account  has  been  given  by  W.  Ken- 
nedy.* Mr.  Kennedy  speaks  of  the  available  ores  as  the 
•'Laminated    Ores"  and    the   "Nodular   Ores,"  both  belong- 

^  First  Ann.  Rep.  Texas  Geol.  Survey,  p.  66 ;  also  Bull.  Oeol.  Soc.  Amer., 
III.,  44.  ^  Mineral  Resources,  1887,  p.  51. 

^  Fiftieth  Congress,  First  Session,  Exec.  Doc.  No.  195. 
*  'Iron  Ores  of  East  Texas,"  Trans.   Amer.   Inst.  Min.  Eng.,  XXIV., 

258,  862. 


98  EEMrS  OBE  DEPOSITS. 

ing,  in  serious  amount,  to  the  greensand  beds  of  the  upper 
Eocene.  An  abundant  series  of  analyses  is  given  which 
shows  the  ores  to  be  in  general  rather  rich  for  limon- 
ites,  and  not  high  in  sulphur  or  phosphorus.  Accord- 
ing  to  the  grade  of  ore  now  demanded  and  obtained  on 
Lake  Superioj,  they  are  seldom  Bessemer  ores,  but  ought  to 
yield  excellent  foundry  irons.  While  the  quantity  is  large, 
the  situation  precludes  the  use  of  any  fuel  but  charcoal,  and 
the  remoteness  of  markets  will  mostly  restrict  the  output  to 
the  comparatively  limited  local  demand.  The  ore  can  be  won 
by  shallow  stripping  or  from  exposed  beds,  up  to  two  feet  or  so 
in  thickness.  The  geological  relations  of  these  ores  are  inter- 
esting and  important  in  that  they  are  derived  from  greensands, 
which  consist  so  largely  of  glauconite,  the  double  silicate  of  iron 
and  potassium,  and  which  are  comparatively  deep-sea  deposits. 
The  formation  of  glauconite '  by  precipitation  from  sea- water, 
and  as  a  filling  of  the  small  chambers  in  minute  shells  and 
organisms  indicates^  a  marine  method  for  the  concentration  of 
iron  oxide.  It  is  significant  that  J.  E.  Spurr  has  lately  advo- 
cated a  similar  source  for  the  ores  of  the  Mesabi  range,  Minn. 
(See  Example  9e.)  Limonite  is  known  in  a  number  of  locali- 
ties in  Colorado.  The  chief  productive  mines  lie  in  Saguache 
County,  near  Hot  Springs.  They  furnish  a  most  excellent  ore 
from  cavities  in  limestones,  which  are  generally,  but  with  no 
great  certainty,  considered  Lower  Silurian.  R.  Chauvenet 
states  that  the  ores  yield  about  43%  Fe  in  the  furnace.^ 

In  Allamakee  County,  in  the  extreme  northeastern  corner 
of  Iowa,  important  deposits  of  rich  limonites  have  been  dis- 
covered on  Iron  Hill  near  the  town  of  Waukon^  and  elsewhere, 

*  On  the  formation  of  greensands,  see  W.  B.  Clark,  Journal  of  Geology, 
II.,  161,  1894. 

*  R.  Chauvenet,  "  Preliminary  Notes  on  the  Iron  Resources  of  Col- 
orado," ^?m.  Rep.  Colo.  State  School  of  Mines,  1885,  p.  21;  "  Iron  Re- 
sources of  Colorado,"  Trans.  Amer.  hist.  Min.  Eng.,  XVIII.,  266.  F.  M. 
Endlich,  Hayden's  Reports,  1^73,  p.  333.  B.  T.  Putnam,  Tenth  Census, 
Vol.  XV.,  p.  483.  C.  M.  Rolker,  "Notes  on  Certain  Iron  Ore  Deposits 
in  Colorado,"  Trans.  Amer.  Inst.  Min.  Eng.,  XIV.,  266.     Rec. 

'  E.  Orr,  "Brown  Hematite  in  Allamakee  County,  Iowa,*'  Amer.  Ge- 
ologist, I.,  129, 1888.  W.  J.  McGee,  "The  Pleistocene  History  of  Northeast 
Iowa,"  Eleventh  Ann.  Rep.  Dir.  U.  S.  Geol.  Siirvey,  548,  1891.  Samuel 
Calvin,  "  Geology  of  Allamakee  Co.,"  Fourth  Ann.  Rep.  Geol.  Surv,  Iowa, 
97,  1894     Rec. 


THE  IRON  SEBIE8  {IN  PART). 


99 


The  superficial  decay  of  the  rocks  in  this  unglaciated  region 
has  been  extensive  and  has  left  a  thick  mantle  of  residual  mate- 
rial. Calvin  estimates  that  a  total  of  about  800  feet  of  Tren- 
ton and  Galena  limestones,  Maquekota  shales  and  Niagara 
limestone  have  disappeared,  leaving  behind  them  the  usual 
clays  and  the  iron  ore.  The  latter  is  in  the  form  of  nodules, 
pipes  and  pots,  and  is  as  much  as  30  feet  thick.  It  has  less 
ocher  and  clay  than  is  usual  in  residual  deposits,  and  this  fact, 
together  with  the  amount  of  iron  oxide,  leads  Calvin  to  infer 
more  of  concentration  than  would  result  by  simple  weathering,. 
The  known  chemical  composition  of  the  beds  which  have  dis- 
appeared indicates  that  the  strata  which  were  formerly  over  the 
area  of  the  ore  would  have  furnished  but  a  fraction  of  it. 


Fig.  13. — Ideal  cross-section  of  Iron  Hill,  near  Waukon,  Allamakee  Co.,  Iowa. 

For  explanation  of  letters,  see  text.     Fourth  Annual  Report 

Iowa  Oeol.  Survey,  p.  101,  1894. 


Professor  Calvin  therefore  suggests,  as  shown  in  the  accom- 
panying figure,  that  a  depression  first  formed,  into  which  the 
iron  oxide  drained  from  a  wide  area.  Having  once  been  con- 
centrated, it  then  settled  down  and  rested  like  a  mantle  upon 
the  hilltop,  which  now  stands  in  relief  although  it  represents 
the  rock  formerly  under  the  depression.  In  the  accompanying 
Fig.  12,  A  is  the  St.  Peter's  sandstone;  J5the  remaining  Tren- 
ton limestone;  the  black  area,  the  present  ore;  CCC  the  origi- 
nal geological  section ;  HJE  the  depressed  outline  after  consid- 
erable weathering  and  erosion,  with  the  production  of  the  ore 
at  D,     FF  is  the  present  outline. 

Much  limonite  occurs  at  Leadville  in  connection  with  the 
lead -silver  ores,  and  is  used  as  a  flux  by  the  lead  smelters. 
Some  grades  low  in  silver  and  rich  in  manganese  have  even 


100  KEMP'S  ORE  DEPOSITS. 

beeD  used  for  spiegel  at  Pueblo.     For  the  geological  relations, 
see  Example  30. 

2.01.16.  Limonites  in  supposed  Carboniferous  limestone 
occur  in  the  East  Tintic  mining  district  in  Utah,  and  seem  to 
be  associated  with  a  decomposed  eruptive  rock,  somewhat  as  at 
Leadville.  The  limonite  is  chiefly  used  as  a  flux  by  lead- 
silver  smelters.^ 

2.01.17.  Example  2a.  Siluro- Cambrian  Limonites. — Beds 
of  limonite  in  so-called  hydromica  (talcose,  damourite),  slates 
and  schists,  often  also  with  limestones  of  the  Cambrian  and 
Lower  Silurian  systems  of  the  Appalachians.  The  great  extent, 
the  geological  relations  and  the  importance  of  these  deposits 
warrant  their  being  grouped  in  a  subtype  by  themselves.  They 
extend  along  the  Appalachians  from  Vermont  to  Alabama,  and 
are  in   the  ** Great   Valley,"  as    it   was  early  termed,  which 

A 

Ssr.^       .  «        I    Engine  House 
vr^nofand  Gravel    ^  1_ 


Probably  Limestone  Slate  Limestone 

(Micaceous) 

Fig.  13. — Geological  Section  of  the  Amenia  Mine,  Dutchess  County,  New  York, 

Ulustratiug  a  Siluro-CamhHaii  limonite  deposit.     After  B^  T. 

Putnam,  Tenth  Census,  Vol.  XV.,  p.  133. 

marks  the  trough  between  the  Aichean  on  the  east  and  the  first 
corrugations  of  the  Paleozoic  rocks,  often  metamorphosed,  on 
the  west.  The  masses  of  limonite  are  buried  in  ochreous  clay, 
and  the  whole  often  preserves  the  general  structure  of  the 
schistose  rocks  which  they  have  replaced.  The  original  string- 
ers of  quartz  remain,  following  the  original  folds.  Dolomitic 
limestone  often  forms  one  of  the  walls,  and  still  less  often  (but 
especially  in  New  England)  masses  of  siderite  are  found 
inclosed.  Manganese  is  at  times  present,  and  in  Vermont  is 
of  some  importance  of  itself. 

2.01.18.  The  deposits  begin  in  Vermont,  where  in  the 
vicinity  of  Brandon  they  have  long  been  ground  for  paint. 
A  curious  pocket  of  lignite  occurs  with  them,  and  affords  Ter- 
tiary fossils.  This  prompted  President  Edward  Hitchcock, 
about  1850,  to  refer  all  the  limonites  to  the  Tertiary,  making 

»  B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  490. 


THE  IRON  SERIES  (IN  PART).  101 

an  instructive  example  of  the  occasional  hasty  generalizations 
of  the  early  days.  Lignite  has  also  been  found  at  Mont  Alto, 
Pa.  In  northwestern  Massachusetts,  at  Richmond  and  West 
Stockbridge;  and  just  across  the  State  line,  in  Columbia  and 
Dutchess  counties,  New  York,  and  at  Salisbury,  Conn.,  the 
mines  are  large,  and  were  among  the  first  worked  in  the 
United  States.  The  limonite  forms  geodes,  or  *'pots,"  pipes, 
stalactitic  masses,  cellular  aggregates,  and  smaller  lumps  from 
which  the  barren  clays  and  ochers  are  removed  by  washing. 
The  ore  is  but  a  fraction  of  the  material  mined  and  occurs  in 
irregular  streaks  through  the  clays,  etc.  It  is  mostly  obtained 
by  stripping  and  open  cuts,  and  only  rarely  by  underground 
mining,  which  would  present  difficulties  with  such  poor  ma- 
terial for  walls.  ^ 

A  gap  occurs  in  the  succession  of  the  deposits  across  south- 
ern New  York  and  New  Jersej^  although  a  few  minor  ones 
are  known  in  the  western  part  of  the  latter  State,  in  the  mag- 
nesian  limestone  of  the  valleys  between  the  hills  of  gneiss.^ 

2.01.19.  In  Lehigh  County  and  to  the  southwest  through 
York  County,  in  eastern  Pennsylvania,  the  limonites  are  again 

'  J.  D.  Dana,  "  Occurrence  and  Origin  of  the  New  York  and  New  Eng- 
land Limonites, 'i^mer.  Jour.  Scl,  iii.,  XIV.,  133,  and  XXVIII.,  398.  Rec. 
E.  Hitchcock,  "Description  of  a  Brown  Coal  Deposit  at  Brandon,  Vt., 
with  an  Attempt  to  Determine  the  Geological  Age  of  the  Principal  Ore 
Beds  of  the  United  States,"  Amer.  Jour.  Sci.,  ii.,  XV.,  95;  Hist.  Geol.  Sur- 
vey of  Vermont,  I.,  233.  See  also  Lesley,  below.  A.  L.  Holley,  "Notes  on 
the  Salisbury  (Conn. )  Iron  Mines  and  Works,"  Trans.  Amer.  Inst.  Min. 
Eng.,  VI.,  220.  J.  P.  Lesley,  "Mont  Alto  (Pa.)  Lignites,"  Proc.  Amer. 
Acad.  Scl,  1864,  463-482;  Amer.  Jour.  Scl,  ii.,  XL.,  119.  L.  Lesque- 
reux,  "On  the  Fossil  Fruits  Found  in  Connection  with  the  Lignite  at 
Brandon,  Vt.,"  Amer.  Jour.  Scl,  ii.,  XXXII. ,  355.  H.  Carvill  Lewis, 
"  The  Iron  Ores  of  the  Brandon  Period,"  Proc.  ^mer.  Assoc.  Adv.  Scl, 
XXIX.,  427,  1880.  J.  F.  Lewis,  "The  Hematite  (Brown)  Ore  Mines, 
etc..  East  of  the  Hudson  River,"  Trans.  Amer.  Inst.  Min.  Eng.,  V.,  216. 
J.  G,  Percival,  Rep.  on  the  Geol.  of  Conn.,  p.  132;  also,  Amer.  Jour.  Scl,  ii., 
II.,  268.  R.  A.  F.  Penrose,  "Report  on  Manganese  Ores,"  Geol.  Survey 
Ark.,  1890,  Vol.  I.  (Contains  many  valuable  descriptions  of  Vermont 
limonites.)  B.  T.  Putnam,  Tenth  Census,  Vol.  XV.  C.  U.  Shepherd, 
"Notice,  etc.,  of  the  Iron  Works  of  Salisbury,  Conn.,"  Amer.  Jour.  Scl, 
i.,  XIX.,  311.  J.  C.  Smock,  Bull.  VII  Neiv  York  State  Museum,  pp.  12,  52. 
N.  H.  and  H.  V.  WMnchell,  "Taconic  Ores  of  Minnesota  and  Western  New 
England,"  Amer.  Geol,  VI.,  263.     1890. 

'^  B.  T.  Putnam,  Tenth  Cenms,  Vol.  XX.,  p.  176.  See  also  Geol.  Survey 
New  Jersey,  1880. 


103  KEMP'S  ORE  DEPOSITS. 

developed  iD  great  amount,  and  rim  southwesterly,  with  few 
gaps,  to  Alabama.  It  is  in  this  portion  that  the  **  Great  Val- 
ley" (called  also  the  Cumberland  Valley,  or  Valley  of  Vir- 
ginia) is  especially  marked.  Wherever  the  great  limestone 
formation.  No.  II.  of  Rogers,  is  developed  the  ores  are  found. 
Thi3  corresponds  to  the  Calciferous,  Chazy,  and  Trenton  of  New 
York.  Limonites  also  occur  still  lower  in  the  Cambrian  at 
about  the  horizon  of  the  Potsdam  sandstone  or  in  the  over 
. lying  slates.  According  to  McCreath,  they  are  divisible  in 
Pennsylvania  into  ores  at  the  top,  ores  in  the  middle,  and  ores 
at  the  bottom  of  the  great  limestone  No.  II.  Those  at  the  top 
form  the  belt  along  the  central  part  of  the  valley  where  the 
Trenton  limestone  underlies  the  Utica  or  Hudson  River  slates. 
Those  in  the  middle  are  connected  with  various  horizons  of  fer- 
ruginous limestones  in  the  Chazy  and  Calciferous.  Those  at 
the  bottom  along  the  north  or  west  part  of  the  South  Mountain- 
Blue  Ridge  range  are  geologically  connected  with  the  Potsdam 
sandstone,  or  the  slates  which  intervene  between  it  and  the 
base  of  the  Calciferous.^  Cobalt  has  been  detected  on  those  of 
Chester  Ridge  by.  Boye,  but  it  is  a  rare  and  unique  discovery.^ 

2.01.20.  The  Siluro-Cambrian  limonites  run  across  Mary- 
land in  Carroll  and  Frederick  counties,  and  arerdfined  to  a  small 
extent.^ 

These  limonites  are  again  strongly  developed  in  the  Shenan- 
doah Valley  along  the  western  base  of  the  Blue  Ridge,  and  in 
southwestern  Virginia  in  the  Cripple  Creek  and  New  River 

*  Second  Pemi.  Survey,  Rep.  MM,  p.  199. 

2  Dr.  Boye,  "Oxyd  of  Cobalt  with  the  Brown  Hematite  of  Chester 
Ridge,  Penn.,  Amer.  Phil.  Soc.,  January,  1846.  P.  Fraser,  Second  Geol. 
Survey  Penn.,  Reps.  C  and  CC;  "  Origin. of  the  Lower  Silurian  Limonites 
of  York  and  Adams  Counties,"  Proc.  Amer.  Phil.  Soc,  March.  1875.  See 
also,  "Remarks  on  a  Paper  of  F.  Prime,"  Idem,  December  21,  1877,  255. 
J.  W.  Harden,  "The  Brown  Hematite  Ore  Deposits  of  South  Mountain 
between  Carlisle,  Waynesborough,  and  the  Southeast  Edge  of  the  Cum- 
berland Valley,"  Trails.  Amer.  Inst.  Min.  Eng.,  I.,  136.  J.  P.  Lesley, 
Summary,  Final  Report,  Vol.  I.,  1892,  pp.  205,  341.  Rec.  A.  S.  McCreath 
Second  Geol.  Survey  Penn.,  Vol.  MM,  199.  F.  Prime,  Second  Geol.  Suiwey 
Penn.,  Reps.  D  and  DD;  "On  the  Occurrence  of  the  Brown  Hematite 
Deposits  of  the  Great  Valley,"  Trans.  Amer  Inst.  Min.  Eng.,  III.,  410; 
Amer.  Jour.  Sci.,  ii.,  IX.,  433;  also,  XL,  62,  and  XV.,  261.  Rec.  B.  T. 
Putnam,  Tenth  Census,  Vol.  XV.,  p.  181. 

^  E.  R.  Benton,  Tenth  Census,  Vol.,  XV.,  p.. 254. 


m 


s 
•a 


•5  ^^^ 


•8? 

•■si 


'E^ 


THE  IRON  SERIES  {IN  PART).  103 

belt.  The  ores  occur  in  connection  with  calcareous  shales,  cal- 
careous sandstones,  and  impure  limestones,  but  have  not  justi- 
fied the  expectations  formed  of  them.  The  geological  relations 
are  similar  to  those  of  the  zinc  ores  described  under  Example 
26,  and  the  pictures  of  the  zinc  mines  will  answer  for  those 
worked  for  limonite.  In  Carroll  County,  Virginia,  the  gossan 
of  the  great  deposit  of  pyrite  is  dug  for  iron  ore.  The  walls, 
however,  are  older  than  the  Cambrian.^ 

2.01.21.  The  limonites  of  eastern  Tennessee  are  the  southern 
prolongation  of  the  area  of  southwest  Virginia.  They  lie 
bet  wen  the  Archean  of  the  Unaka  range  on  the  east,  and  the 
Upper  Silurian  strata  in  the  foot  of  the  Cumberland  tableland 
on  the  west.  The  ores  outcrop  in  the  longitudinal  valleys  or 
'*coves."  The  bottoms  of  these  valleys,  according  to  Safford 
(p.  449),  are  formed  by  the  shales,  slates,  and  magnesian  lime- 
stones of  the  Knox  group,  and  in  the  residual  clay  left  by  their 
alteration  the  ore  is  found.  The  gossan  of  the  neighboring 
veins  of  Cjppper  pyrites,  best  known  at  Ducktown  (see  Example 
16),  was  originally  exploited  for  iron.^  The  Tennessee  limon- 
ite extends  across  northwestern  Georgia,  and  still  farther  east 

'  E.  R.  Benton,  Tenth  Cenms,  Vol.  XV.,  p.  361.     J.  L.  Campbell,  "Re 
port  on  the  Mineral  Prospects  of  the  St.  Mary  Iron  Property,"  etc. ,  The  Vir 
ginias,  February,  1883,  p.  19.     See  also  The  Virginias,  January,  1880,  p. 
4;  March,  p.  43.     F.  P.  Dewey,  "The  Rich  Hill  Iron  Ores,"  Trans.  Amer. 
Inst.  Min.  Eng.,  X.,  77.     W.  M.  Fontaine,  "  Notes  on  the  Mineral  Deposits 
of  Certain  Localities  in  the  Western  Part  of  the  Blue  Ridge,"  The  Vir 
ginias,  March,   1883,  p.  44;  April,  p.  55;  May,  p.  73;  June,  p.  93.     B.  S 
Lyman,   "On  the  Lower  Silurian  Brown    Hematite  Beds  of  America,' 
Proc.   Amer.  Assoc.  Adv.  Sei.,  XVII.,  114.     A.   S.  McCreath,   "The  Iron 
Ores  of  the  Valley  of  Virginia,"  Trans.  Amer.  Inst.  Min.  Eng.,  XII.,  103 
Engineering  and  Mining  Journal,   June,  1883,  p.  334.     E.  C.  Moxham 
"The  Great  Gossan  Lead   of  Virginia,"  Trans.  Amer.  Inst.  Min.  Eng. 
XXL,  133.     E.  C.   Pechin,  "The  Iron  Ores   at   Buena  Vista,  Rockbridge 
County,  Virginia."  Engineering  and  Mining  Journal,  Aug.  3,  1889,  p.  92 
"Mining  of  Potsdam  Brown  Ores  in  Virginia,"  Engineering  and  Mining 
Journal,  Sept.  19,  1891,  p.  337;  "Iron  Ores  of  Virginia  and  their  Develop- 
ments,"  Trans.  Amer.  Inst.  Min.  Eng.,  XIX.,  101;  "Ore  Supply  for  Vir- 
ginia Furnaces,"  Engineering  and  Mining  Journal,  Vol.  LI.,  1891,  pp.  323, 
349.     Rec. 

'  J.  M.  Safford,  Geol.  of  Tenn.,  p.  448,  1869.  B.  Willis,  Tenth  Census, 
Vol.  XV.,  p.  331.  The  best  works  of  reference  are  the  recent  folios  of  the 
U.  S.  Geological  Survey,  which  cover  a  large  part  of  southeastern  Ten- 
nessee and  the  neighboring  parts  of  Alabama  and  Georgia, 


104  KEMP'S  ORE  DEPOSITS. 

the  so-called  Huronian  limestones  of  North  Carolina  also  enter 
the  State.  But  as  even  these  so-called  Huronian  schists  and 
associated  marbles  have  been  considered  by  F.  P.  Bradley  to 
be  metamorphosed  Silurian  (Cambrian),  the  ores  may  also  be- 
long under  Example  2a.  The  well-determined  Siluro-Cambrian 
rocks  form  but  a  narrow  belt  of  no  great  importance  in  North 
Carolina.^ 

The  limonites  are  again  strongly  developed  in  Alabama  and 
furnish  a  goodly  proportion  of  the  ore  used  in  the  State. 
They  form  a  belt  lying  east  of  the  Clinton  ores  (Example  6), 
later  described.  As  in  Tennessee,  they  are  associated  with 
strata  of  the  Knox  group. ^ 

2.01.23.  Origin  of  the  .  Siluro- Cambrian  Limonites. — 
Dr.  Jackson,  of  the  First  Pennsylvania  Survey,  argued  in  1839^ 
that  they  originated  in  situ;  that  is,  by  the  alteration  of  the 
rocks  in  and  with  which  they  occur.  Percival,  in  his  report 
on  the  Geology  of  Connecticut  in  1842  (p.  132),  attributed  them 
to  the  alteration  of  pyrite  in  the  neighboring  mica-slate. 
Prime,  in  Pennsylvania,  in  1875  and  1878  (Reports  D  and 
DD),  considers  that  the  iron  has  been  obtained  by  the  leaching 
of  the  neighboring  dolomites  and  slates,  it  being  in  them  either 
as  silicate,  carbonate  or  sulphide;  that  the  ore  has  reached  its 
position  associated  with  the  slates,  because,  being  impervious, 
they  retained  the  ferruginous  solutions;  and  that  the  potash 
abundantly  present  in  the  slates  probably  assisted  in  precipita- 
ting it.*  Frazer,  in  1876,^  in  studying  the  beds  of  York  and 
Adams  counties,  Pennsylvania,  found  the  hydromica  slates 
filled  with  the  casts  of  pyrite  crystals,  and  held  these  to  have  been 
the  sources  of  the  iron,  because  they  would  afford  ferrous  sul- 
phate and  sulphuric  acid.    The  latter  reacted  on  the  alkali  of  the 

^  F.  P.  Bradley,  "The  Age  of  the  Cherokee  County  Rocks,  North  Car- 
olina," Amer.  Jour.  Set,  iii.,  IX.,  279,  320;  B.  Willis,  Tenth  Census,  Vol. 
XV.,  p.  367. 

""  W.  M.  Chauvenet,  Tenth  Census,  Vol.  XV.,  p.  383.  H.  McCalley,  "  Li- 
monites of  Alabama  Geologically  Considered,"  Engineering  and  Mining 
Journal,  Dec.  19,  1896,  583.  For  other  references  to  Alabama  iron  ore 
deposits,  see  under  Example  6.  The  fohos  of  the  U.  S.  Geological  Survey 
bearing  on  this  region  should  be  consulted. 

•  Ann.  Rep.  First  Pa.  Survey,  1839. 

*  Trans.  Amer.  Inst.  Min.  Eng.,  II.  410. 
"  Second  Pa.  Survey,  Rep.  C,  p.  136. 


THE  IRON  SERIES  {IN  PART).  105 

slates,  producing  sodium  sulphate.  This,  meeting  calcium  car- 
bonate afforded  calcium  sulphate  and  sodium  carbonate,  which 
latter  precipitated  the  iron.  Calcium  carbonate  alone  is,  how- 
ever, abundantly  able  to  precipitate  iron  carbonate  and  ox  ide  from 
both  ferrous  and  ferric  sulphate  solutions  (even  when  neutral) 
without  the  introduction  of  the  alkali,  although  this  might 
account  for  the  alteration  of  the  slates.^ 

2.01.24.  J.  D.  Dana  has  written  at  length  on  the  New 
England  and  New  York  deposits,  and  finds  them  always  at  or 
near  the  junction  of  a  stratum  of  limestone,  proved  in  many 
cases  to  be  ferriferous,  and  sometimes  entirely  siderite,  and  one 
of  hydromica  slate  or  mica  schist.  In  several  mines  bodies  of 
unchanged  spathic  ore  are  embedded  in  the  limonite.  Hence 
Professor  Dana  explains  the  limonite  as  derived  by  the  weath- 
ering of  a  highly  ferruginous  limestone,  from  which  the  limon- 
ite has  been  left  behind  by  the  removal  of  the  more  soluble 
elements,  so  as  practically  to  replace  the  limestone  in  connec- 
tion with  other  less  soluble  matter.  The  limonite  has  also  at 
times  replaced  the  schists,  probably  deriving  its  substance  in 
part  from  iron-bearing  minerals  in  them,  and  changing  these 
rocks  to  the  ochers  and  clays  now  found  with  the  ores.  These 
views  are  undoubtedly  very  near  the  truth  for  the  region  stud- 
ied, and  have  been  corroborated  by  observations  of  the  writer. 
(Cf.  also  Example  4.)  Weathering  limestones  do  furnish 
residual  clay,  ocher,  etc.,  as  is  shown  by  the  deposits  of  western 
Kentucky  and  Tennessee  under  Example  2. 

2.01.25.  Another  hypothesis  early  formulated  and  advo- 
cated by  many  is  that  the  limonites  have  been  derived  from  the 
surface  drainage  of  the  old  Appalachian  highlands,  then  have 
been  precipitated  in  still  water  and  have  been  buried  up  where 
they  are  now  found.  A  precipitation  around  the  shores  of  a 
ferruginous  sea  has  also  been  urged  on  the  analogy  of  certain 
explanations  of  the  Clinton  ore.  (Example  6.)  Their  supposed 
Tertiary  age  has  already  been  remarked.  All  these  views  are 
essentially  hypothetical  and  have  no  good  foundation.^ 

*  See  F.  P.  Dunnington,  "On  the  Formation  of  Deposits  of  Manganese," 
Amer.  Jour.  Sci.,  iii.,  XXXVI.,  p.  175,     (Experiments  10  and  11.) 

""  See  H.  D.  Rogers,  Trans.  Asso.  Amer.  Geol.  and  Nat.,  1842,  p.  345;  E. 
Hitchcock,  Geol.  Vt.,  Vol.  I.,  p.  233;  J.  P.  Lesley,  Iron  Manufacturers* 
Guide,  p.  501;  Rep.  A,  Second  Pa.  Surrey,  p.  83;  J.  S.  Newberry, 
International  Review,  November  and  December,  1874. 


106 


KEMP'S  ORE  DEPOSITS. 


ANALYSES   OF  LIMONITES. 

2.01.26.  All  published  analyses,  except  when  forming  a 
sufficiently  large  and  continuous  series  from  the  output  of  any 
one  mine,  are  to  be  taken  with  caution.  Ores  necessarily  vary 
much,  and  a  single  analysis  or  a  selected  set  may  give  a  very 
wrong  impression.  The  percentage  in  iron  is  different  for  dif- 
ferent parts  of  the  same  ore  body.  The  few  that  follow  have 
been  selected  to  show  the  range  and  the  average.  The  highest 
are  exceptionally  good,  the  lowest  less  than  the  average,  and  the 
medium  values  indicate  approximately  the  general  run. 
Limonites  afford  from  40  to  50%  Fe  as  actually  exploited,  but 
it  is  not  difficult  to  find  individual  analyses  that  run  higher. 
They  are  not,  generally  speaking,  Bessemer  ores. 


ANALYSES   OF  LIMONITES. 


Fe. 

P. 

S. 

SiO, 

AlaOg 

H,0. 

Berkshire  County,  Mass '. . 

47.52 
50.48 
46.45 
39.72 

0.187 
0.353 
0.370 
0.059 

Connecticut 

Dutchess  County,  New  York 

Staten  Island 

0.391' 
0.020 

14.100 

14.190 

5.165 

3.056 
3.590 

12.41 

Pennsylvania 

56.30    0.125 

Virginia  (Low  Moor) 

43.34 
50.91 
50.89 

0.636 
0.237 
0  225 

Tennessee  (Lagrange  Furnace)  . . 
Alabama 

0.200 

20.000 

0.700 

Colorado 

53.37    0.034 

Colorado,  average 

43.00 
44.71 
59.92 

0.030 
0.666 

18  00 

Prosser  mine,  Oregon. 

Pure  mineral 

14.40 

SIDERITE   OR  SPATHIC   ORE. 

2.01.27.  Siderite  is  the  protocarbonate  of  iron.  As  a  min- 
eral it  often  contains  more  or  less  calcium,  magnesium,  and 
manganese.  When  of  concretionary  structure,  embedded  in 
shales  and  containing  much  clay,  the  ore  is  called  clay  iron- 
stone. -When  the  concretions  enlarge  and  coalesce,  so  as  to 
form  beds  of  limited  extent,  generally  containing  much  bitumi- 
nous matter,  they  are  called  black-band,  and  are  chiefly  devel- 
oped in  connection  with  cpal  seams. 

2.01.28.  Examples.  C/az/Jron5^07ie.— The  name  is  applied 
to  isolated  masses  of  concretionary  origin  (kidneys,  balls,  etc.) 


THE  IRON  8EBIE8  {IN  PART).  107 

which  may  at  times  coalesce  to  form  beds  of  considerable 
extent.  They  are  usually  distributed  through  shales,  and  on 
the  weathering  of  the  matrix  are  exposed  and  concentrated. 
They  are  especially  characteristic  of  Carboniferous  strata  and 
differ  from  black-band  only  in  the  absence  of  bituminous  mat- 
ter and  in  the  consequent  drab  color.  They  weather  to  limon- 
ite,  generally  in  concentric  shells  with  a  core  of  unchanged 
carbonate  within.  Fossil  leaves  or  shells  often  furnish  the 
nucleus  for  the  original  concretion,  and  are  thus,  as  at  Mazon 
Creek,  111.,  beautifully  preserved.  When  in  beds  the  ore  is 
sometimes  called  flagstone  ore;  when  broken  into  rectangular 
masses  by  joints,  it  is  called  block  ore. 

2.01.29.  Example  3a.  jB/acA;-6and— The  name  is  applied 
to  beds  consisting  chiefly  of  carbonate  of  iron  with  more  or  less 
earthy  and  bituminous  matter.  They  are  of  varying  thickness, 
thoiigh  rarelj"  more  than  six  feet,  and  are  almost  invariably 
associated  with  coal  seams.  They  are  thus  especially  found  in 
the  Carboniferous  system,  and  to  a  far  less  degree  in  the  east- 
ern Jura-Trias.  They  are  also  recorded  with  the  Cretaceous 
coals  of  the  West.  It  is  not  possible  to  separate  the  two  varie- 
ties in  discussing  their  distribution.  The  various  productive 
areas  are  taken  up  geographically,  beginning  with  the  Appa- 
lachian region. 

2.01.30.  The  carbonate  ores  are  of  great  importance  in  the 
Carboniferous  of  western  Pennsylvania  and  in  the  adjacent 
parts  of  Ohio,  West  Virginia  and  Kentucky.  In  these  States 
the  system  is  subdivided  in  connection  with  the  coal,  from 
above  downward,  as  follows :  I.  The  Upper  Barren  Measures, 
Permo-Carboniferous,  or  Dunkard's  Creek  Series;  II.  The 
Upper  Productive  Coal  Measures,  or  Monongahela  River 
Series;  III.  The  Lower  Barren  Measures,  or  Elk  River  Series; 
IV.  The  Lower  Productive  Coal  Measures,  or  Allegheny 
River  Series;  V.  The  Great  or  Pottsville  Conglomerate.  In 
the  Upper  Barren  Measures  of  Pennsylvania,  according  to 
McCreath,  there  is  hardly  a  stratum  of  shale  or  sandstone 
without  clay  ironstone  nodules,  but  no  continuous  beds  are 
known.*  The  deposits  are  not  of  great  actual  importance,  and 
are  worthy  of  only  passing  mention.  In  the  Upper  Productive 
Coal  Measures  some  ore  occurs  associated  with  the  Waynes- 

^ Second  Pa.  Survey,  Rep.  K,  p.  386;  MM,  p.  159. 


108  KEMP'S  ORE  DEPOSITS. 

burg  coal  seam,  and  again,  just  under  the  Pittsburg  seam, 
there  is  considerable  known  as  the  Pittsburg  Iron  Ore  Group. 
This  latter  ore  becomes  of  great  importance  in  Fayette  County, 
and  extends  through  several  beds/  The  Lower  Barren  Meas 
ures  in  Pennsylvania  also  contain  carbonate  ore  in  a  number 
of  localities.  The  most  persistent  is  the  Johnstown  ore  bed, 
near  the  base  of  the  series.  There  are  two  additional  beds  just 
over  the  Mahoning  sandstone. 

The  Lower  Coal  Measures  are  the  chief  ore  producers  in  all 
the  States.  They  furuish  balls  of  clay  ironstone  in  very  many 
localities  in  western  Pennsylvania,  which  will  be  found 
recorded  with  many  additional  references  in  Report  MM,  p. 
174,  Pa.  Qeol.  Survey.  The  nodules  are  scattered  through 
clay  and  shales.  The  so-called  Ferriferous  limestone,  which 
lies  a  few  feet  below  the  Lower  Kittanning  coal  seam,  affords 
in  its  upper  portion  varying  thicknesses  of  carbonate  ore,known 
as  **buhrstone  ore,"  which  is  altered  in  large  part  to  limonite. 
Some  little  carbonate  ore  was  found  in  the  early  days  in  the 
anthracite  measures  of  eastern  Pennsylvania.  Sevei'al  beds  of 
the  same  occur  in  the  Great  Conglomerate  and  its  underlying 
(Mauch  Chunk)  shales.  They  are  chiefly  developed  in  south- 
western Pennsylvania  (Report  KK),  and  may  form  either 
entire  beds  or  disseminated  nodules.  The  limonites  of  the 
Marcellus  stage  that  pass  into  carbonates  in  depth  in  Perry  and 
the  neighboring  counties  have  already  been  mentioned  under 
Example  2.  In  West  Virginia  both  Upper  and  Lower  Meas- 
ures afford  the  ore.  From  the  latter  black-band  is  extensively 
mined  on  Davis  Creek,  near  Charleston.^ 

2.01.31.  In  Ohio  a  number  of  nodular  deposits  are  known, 
but  practically  no  ore  is  produced  above  the  Mahoning  sand- 
stone of  the  Lower  Coal  Measures.  Below  this  sandstone  the 
ores  are  extensively  developed.  They  extend  up  and  down  the 
eastern  part  of  the  State,  and  are  both  black- band  and  cla}^ 
ironstone.  Orton  identifies  twelve  different  and  well-marked 
horizons  distributed  through  the  Lower  Measures.  He  distin- 
guishes the  stratified  ores,  mostly  black-band,  and  the  concre- 


»  Rep.  MM,  p.  162;  KK,  p.  Ill;  L,  p.  98. 

^  M.  F.  Maury  and  W.  M.  Fontaine,  Resources  of  West  Virginia,  1876, 
p.  247. 


THE  IRON  SERIES  {IN  PART).  109 

tionary  ores,  including  kidney  ores,  block  ores,  and  limestone 
ores.^ 

2.01.32.  The  general  distribution  of  the  iron  ores  of  Ken- 
tucky has  already  been  outlined  under  Example  2.  The  Hang- 
ing Rock  region  is  a  southern  prolongation  of  the  Ohio  district 
of  the  same  geological  horizon.  P.  N.  Moore  has  classified  the 
local  ores  as  limestone  ores,  which  are  associated  with  lime- 
stone, block  ores,  and  kidney  ores.  The  last  two  names  refer 
to  the  fracture  or  shape  of  the  masses.  They  occur  associated 
with  the  usual  clay  and  shale.  Farther  west,  between  the  Ken- 
tucky and  Red  rivers,  are  the  other  deposits,  the  principal  one 
of  which  comes  low  in  the  series,  just  over  the  Subcarbonifer- 
ous  limestone.'' 

2.01.33«  Small  quantities  of  black-band  have  been  found  in 
the  Deep  River  coal  beds,  in  North  Carolina,  associated  with 
the  Triassic  coals. ^ 

A  large  bed,  or  series  of  beds,  has  recently  been  reported 
from  Enterprise,  Miss.,  in  strata  of  the  Claiborne  stage.  They 
run  from  ten  to  eighteen  feet  in  thickness, and  extend  for  miles.* 
Scattered  nodules  have  been  noted  at  Gay  Head,  Martha's  Vine- 
yard.^ Carbonate  ores  are  as  yet  of  no  importance  in  the  coal 
measures  of  the  Mississippi  Valley.  They  have  been  found 
associated  with  the  Cretaceous  coals  of  Wyoming  and  Colo- 
rado— and  indeed  the  first  pig  iron  of  the  latter  State  was  made 
from  them  in  Boulder  County — but  they  are  not  an  important 
source  of  ore."  An  extended  bed  of  very  excellent  carbonate 
has  recently  been  discovered  with  coal  near  Great  Falls,  in  the 
Sand  Coulee  region  of  Montana.     Being  near  coal,  limestone, 

^  Geol.  of  Ohio,  V.,  p.  378,  and  supplemental  report  on  the  Hanging 
Rock  region  in  Vol.  III. 

"^  P.  N.  Moore,  "  On  the  Hanging  Rock  District  in  Kentucky,"  Kentucky 
Oeol.  Survey,  Vol.  I.,  Part  3. 

"  B.  Willis,  Tenth  Census,  Vol.  XV.,  p.  306;  W,  C.  Kerr,  Geology  of 
North  Carolina,  1875,  p.  225. 

*  A.  F.  Brainard,  "  Spathic  Ore  at  Enterprise,  Miss.,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XIV.,  146. 

*  W.  P.  Blake,  "Notes  on  the  Occurrence  of  Siderite  at  Gay  Head, 
Mass.,"  Trans.  Amer.  Inst.  Min.  Eng.,  IV.,  113. 

®  R.  Chauvenet,  "Notes  on  the  Iron  Resources  of  Colorado,"  Ann.  Rep. 
Colo.  School  of  Mines,  1885,  1886;  Trans.  Amer.  Inst.  Min.  Eng.,  XVIIL, 


110 


KEMP'S  ORE  DEPOSITS. 


and  other  iron  ores,  it  promised  to  be  of  considerable  impor- 
tance/ 

2.01.34.     Example  4.     Burden  Mines,  near  Hudson,  N.  Y. 
Elongated  lenticular  beds  of  clay  ironstone,  passing  into  sub- 


crystalline  siderite,  enclosed  conformably  between  underlying 

slates,  and    overlying    calcareous    sandstone,  of  the    Hudson 

River  stage.     The  ore  occurs  in  four  "basins,'*  which  outcrop 

*  O.  C.  Mortson,  Mineral  Resources  U.  S.,  1888,  p.  34. 


THE  IRON  SERIES  {IN  PART).  HI 

along  the  western  slope  of  a  series  of  moderate  hills,  just  east 
of  the  Hudson  River.  The  hills  have  been  shown  by  Kimball 
to  be  the  eastern  halves  of  anticlinal  folds  now  reduced  by  ero- 
sion to  easterly  dipping  monoclines.  The  western  half  of  the 
ore  bodies  has  been  eroded  away,  leaving  an  outcrop  44  feet 
thick  as  a  maximum,  which  pinches  out  along  the  strike  and 
dip.  The  basins  extend  from  southwest  to  northeast,  parallel  to 
the  trend  of  the  hills.  The  beds  are  more  or  less  faulted.  The 
southern  part  of  the  second  basin  affords  Bessemer  ores,  but  the 
others  are  too  high  in  phosphorus.  At  this  point  the  principal 
mining  has  been  done.  According  to  Olmstead,  some  varieties 
are  richer  in  phosphorus  than  others,  but  they  are  so  intimately 
mixed  as  not  to  be  practicably  separated.  Up  to  1889  the 
mines  had  produced  450,000  tons  of  roasted  Bessemer  ores. 

2.01.35.  In  their  geological  relations  the  ores  are  of  the 
greatest  interest,  as  they  occur  in  the  western  limit  of  the 
metamorphic  belt,  which  forms  the  basis  of  the  Taconic  con- 
troversy, yet  in  strata  which  have  been  identified  by  fossils. 
Beds  of  limonite  hitherto  regarded  as  Siluro  Cambrian  occur  to 
the*  east;  and  should  further  study,  on  the  lines  developed 
chiefly  by  J.  D.  Dana,  W.  B.  Dwight,  and  C.  D.  Walcott, 
clear  up  their  stratigraphical  relations,  the  work  done  in  devel- 
oping the  structure  of  the  siderite  basins,  as  pointed  out  by 
Kimball,  may  be  of  great  aid  in  explaining  them.  Very 
similar  bodies  of  siderite  occur  with  these  limonites.  (Exam- 
ple 2a.)  The  Burden  ores  are  relatively  high  in  magnesia, 
and  this  leads  Kimball  to  suggest  their  original  deposition 
from  the  off-shore  drainage  of  the  basic  rocks  of  the  Archean 
highlands.  Further,  it  may  be  added  that  the  ores  in  their 
lenticular  shape  are  highly  suggestive  of  a  possible  origin  for 
magnetite  deposits,  and  they  are  again  referred  to  under  "Mag- 
netite." Other  deposits  of  siderite  in  the  shales  of  the  Marcel- 
lus  stage  are  known  and  were  formerly  worked  at  Wawar- 
sing,  Ulster  County,  across  the  Hudson  River.^ 

'  J.  P.  Kimball,  "Siderite  Basins  of  the  Hudson  River  Epoch,"  Amer. 
Jour.  Set,  III.,  xl.  155.  I.  Olmstead,  "Distribution  of  Phosphorus  in  the 
Hndson  River  Carbonate,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVIII.,  252.  R 
W.  Raymond,  "The  Spathic  Ores  of  the  Hudson  River,"  Trans.  Amer.  Inst. 
Min.  Eng.,  IV.,  309.  J.  C.  Smock,  Bulletin  VII  of  New  York  State  Mus 
eum  on  Iron  Ores,  p.  62. 


112  KEMP'S  ORE  DEPOSITS. 

2.01.36.  Example  5.  Roxbury,  Conn.  A  fissure  vein  in 
gneiss,  six  to  eight  feet  wide,  of  crystalline  siderite,with  which 
are  asociated  quartz  and  a  variety  of  metallic  sulphitles, 
galena,  chalcopyrite,  zinc  blende,  etc.  Although  productive  in 
former  years,  it  is  no  longer  worked,  and  is  of  scientific  more 
than  economic  interest,  being  a  unique  deposit.  It  has  fur- 
nished many  fine  cabinet  specimens.^ 

2.01.37.  The  spathic  ores  are  the  lowest  in  iron  of  all,  and 
in  the  raw  state  are  often,  if  not  always,  far  below  the  limit 
of  profitable  treatment.  Calcination,  however,  drives  off  the 
carbonic  acid  and  moisture  and  brings  the  percentage  of  iron  up 
to  a  merchantable  grade.  The  later  development  of  the  iron 
industry  in  this  country  has  been  unfavorable  to  spathic  ores, 
and  year  by  year  their  amount  has  decreased  until  now  it  is 
nearly  obliterated,  being  only  about  one  per  cent   of  the  total. 

2.01.38.  The  subjects  of  limonite  and  siderite  cannot  well 
be  passed  without  further  reference  to  their  genetic  relations  as 
connected  with  limestone.  The  processes  involved  concern  not 
alone  these  ores,  but  also  the  more  metamorphic  forms — hema- 
tite and  magnetite — into  which  they  may  pass  by  reasofi  of 
subsequent  changes.  It  was  stated  earlier  (2.01.05)  that  cal- 
cium carbonate  precipitated  from  ferric  salts,  ferric  hydrate,  and 
from  ferrous  salts,  ferrous  carbonate,  which  in  the  presence  of 
oxygen  quickly  changed  to  ferric  hydrate.  Jo  P.  KimbalP  has 
recently  added  a  note  on  the  chemistry  of  the  process  which 
modifies  it  somewhat.  He  brings  out  the  fact  that  it  is  the 
hydrous  carbonate  of  iron  which  is  precipitated  from  ferrugi- 
nous salts  by  the  various  alkaline  carbonates,  and  that,  being 
an  unstable  salt,  it  quickly  oxidizes  to  a  hydrous  oxide.  From 
this  the  argument  is  made  that  bodies  of  siderite,  or  anhydrous 
ferrous  carbonate,  could  not  have  originated  by  direct  precipi- 
tation, but  must  have  done  so  by  pseudomorphous  replacement 
of  limestone.  Dr.  Kimball  then  follows  out  the  possible  meta- 
morphism  or  changes  of  these  bodies  to  other  forms  of  iron  ore, 

^  J.  P.  Lesley,  Iron  Manufacturers'  Guide,  p.  649.  C.  U.  Shepherd, 
''Report  on  the  Geology  of  Connecticut,"  1837,  p.  30,  Amer.  Jour.  Sci.,  I., 
xix.  311. 

'  J.  P.  Kimball,  ' '  Genesis  of  Iron  ores  by  Isomorphous  and  Pseudomor- 
phous Replacement  of  Limestone,"  A7ner.  Jour.  Sci.,  September,  1891,  p 
231,  and  conclusion  in  the  ^?/ier.  Geol.,  December,  1891. 


THE  IRON  SERIES  {IN  PART).  113 

citing,  however,  among  many  that  are  unexceptionable,  some 
instances  as  possible  examples  for  which  the  field  relations  give 
but  slight  justification.  The  specular  ores  with  the  porphyries 
of  Missouri  are  of  this  latter  character,  and  the  work  of  C.  H. 
Smyth,  Jr.,  later  cited,  on  the  oolitic  Clinton  hematites  gives 
strong  ground  for  thinking  them  accumulations  in  shallow 
waters  as  concentric  layers  upon  original  nuclei  of  quartz. 

2.01.39.  While  the  importance  of  limestone  as  a  cause  of 
the  formation  of  bodies  of  iron  ore  cannot  be  too  highly  empha- 
sized, and  it  is  quite  possible  that  some  puzzling  ones,  such  as 
many  magnetite  beds,  have  originated  in  this  way,  and  that 
the  limestone  has  so  entirely  disappeared  as  to  give  slight  clue 
to  its  original  presence;  yet  it  must  not  be  overlooked  that 
siderite  often  does  form  in  nature  quite  independently  of  cal- 
cite,  and  that  conditions  must  be  often  such  as  to  make  this 
possible.  If  vuggs  with  free  crystals,  or  if  cleavage  masses 
with  the  proper  angle  occur  in  a  deposit,  we  must  admit  that 
the  siderite  is  produced  under  circumstances  not  different  from 
those  which  prevailed  during  the  formation  of  the  walls  or  of 
the  massive  mineral.  Repeated  experience  indicates  that  these 
are  not  extraordinary. 


CHAPTER  II. 

THE  IRON  SERIES  CONTINUED— HEMATITE,  RED  AND  SPECULAR. 

2.02.01.  The  sesquioxide  of  iron,  F2O3,  is  always  of  a  red 
color  when  in  powder.  If  it  is  of  earthy  texture,  this  color 
shows  in  the  mass,  and  the  ore  is  called  red  hematite ;  if  the 
ore  is  crystallized,  the  red  color  is  not  apparent,  and  the  bril- 
liant luster  of  the  mineral  gives  it  the  name  specular  hematite. 
The  red  hematites  are  first  treated. 

2.02.02.  Example  6.  Clinton  Ore.— Wherever  the  Clinton 
stage  of  the  Upper  Silurian  outcrops,  it  almost  invariably  con- 
tains one  or  more  beds  of  red  hematite,  interstratified  with  the 
shales  and  limestones.  These  ores  are  of  extraordinary  persist- 
ence, as  they  outcrop  in  Wisconsin,  Ohio  and  Kentucky  in  the 
interior,  and  then  beginning  in  New  York,  south  of  Lake 
Ontario,  they  run  easterly  across  the  State.  Again  in  Penn- 
sylvania they  follow  the  waves  of  the  Appalachian  folds  and 
extend  south  into  West  Virginia  and  Virginia  in  great 
strength.  They  are  found  in  eastern  Tennessee  and  northwest- 
ern Georgia,  and  finally  in  Alabama  are  of  exceptional  size 
and  importance.  The  structure  of  the  ore  varies  somewhat. 
At  times  it  is  a  replacement  of  fossils,  such  as  crinoid  stems, 
molluscan  remains,  etc.  (fossil  ore) ;  again  as  small  oolitic  con- 
cretions, like  flaxseed  (flaxseed  ore,  oolitic  ore,  lenticular  ore); 
while  elsewhere  it  is  known  as  dyestone  ore.  The  ore  in  many 
places  is  really  a  highly  ferruginous  limestone,  and  below  the 
water  level  in  the  unaltered  portion  it  often  passes  into  lime- 
stone, while  along  the  outcrop  it  is  quite  rich. 

2.02.03.  In  Dodge  County,  southeastern  Wisconsin,  the  ore 
in  14  to  26  feet  thick,  and  consists  of  an  aggregate  of  small 
lenticular  grains.^     In  Ohio  it  outcrops  in  Clinton,  Highland 

^  T.   C.  Chamberlin,  Geol.  Survey  Wis.,  Vol.  I.,  p.  179.     R.  D.  Irving, 
"  Mineral  Resources  of  Wisconsin,"  Trans.  Amer.  Inst.  Min.  Eng.,  VIII. 
478;  Geol.  Survey  Wis.,  Vol.  I.,  p.  625. 


TEE  IRON  SERIES  CONTINUED.  115 

and  Adams  counties,  in  the  southwestern  portion  of  the  State 
along  the  flanks  of  the  Cincinnati  Arch,  but  it  is  thin  and  poor 
in  iron,  although  rich  in  fossils.^  A  small  area  of  the  Clinton 
has  furnished  considerable  ore  in  Bath  County,  Kentucky, 
where  it  is  altered  to  limonite.^ 

2.02.04.  Coming  eastward,  the  limestones  and  the  shales  of 
the  Clinton  outcrop  in  the  Niagara  River  gorge  in  New  York, 
but  show  no  ore.  This  appears  first  in  quantity  in  Wayne 
County,  a  hundred  miles  east  and  just  south  of  Lake  Ontario. 
One  bed  reaches  20  to  22  inches.     Farther  east  are  the  Sterling 


~  '         '       ~         jlZ ! ^  i ~ I      '  ~ 


I         li   J L_  _ .     LJ     I  _ 


Till  loi 


Limestone  0-6 


'_   J I  _J    _L_       LI  _J I    I    i       '      -' l_J_  I  _ 

^  —  ;  -  --I-  i—ir '  V — r!;=^-T-'  -n  '-^ 

Fig.  16. — Clinton  Ore,  Ontario,  Wayne  County,  New  York.     After 
C.  H.  Smyth,  Jr. 

mines,  in  Cayuga  County ;  and  again  near  Utica,  in  the  town  of 
Clinton,  which  first  gave  the  ore  its  name,  it  is  of  great  eco- 
nomic importance.  There  are  two  workable  beds,  the  upper 
of  which,  with  a  thickness  of  about  two  feet,  is  the  only  one 
now  exploited.  Beneath  this  are  12  or  15  inches  of  shale,  and 
then  the  second  bed  of  8  inches  of  ore.^  Some  25  feet  over  the 
upper  bed  is  still  a  third,  which  is  too  low  grade  for  mining. 
It  is  four  to  six  feet  thick,  and  is  locally  called  red  flux.  It 
consists  of  pebbles  and  irregular  fragments  of  fossils,  which 
are  coated  with  hematite  and  cemented  with  calcite. 

•  J.  S.  Newberry,  Geol.  of  Ohio,  Vol  III.,  p.  7.  E.  Orton,  Geol.  of  Ohio, 
Vol  v.,  p.  371. 

»  N.  S.  Shaler,  Geol.  of  Ky.,  Vol.  III.,  163. 

'  A.  H.  Chester,  "  The  Iron  Region  of  Central  New  York,"  address  be- 
fore the  Utica  Merchants  and  Manufacturers'  Association,  Utica,  1881. 
J.  C.  Smock,  Bull.  VII  of  N.  Y.  State  Museum,  June  1889.  C.  H. 
Smyth,  Jr.,  "On  the  Clinton  Iron  Ore,"  Arner.  Jour.  Sci.,  June,  1892,  p. 
487.     Zeitschr.  fiir  prakt.  Geologie,  ISM,  ^04. 


116 


KEMP'S  ORE  DEPOSITS. 


2.02.05.  The  rocks  of  the  Clinton  thicken  greatly  in  Penn- 
sylvania  and  run  south  westward  through  the  central  part  of 
the  State.  Six  different  ore  beds  have  been  recognized,  of  which 
the  lower  are  probably  equivalent  to  the  Southern  dyestone 


ores. 


Calcareous  Sandstonie 

and  I 

thin  Shale  layers    CO* 


Non-Oolitic  Ore    i 
(Red  Flux)       6 


Calcareous        , 
Sandstone     6 


Blue  Shale 

and  thin  f 

Sandstone  layers   16' 


Oolitic  Ore  2 

Shale  2'  , 
Oolitic  Ore  1 
Blue  Shale 

and  thin  , 

Sandstone  layers  100  X 


Fig.  17.— Clinton  Ore,  Clinton,  New  York.     After  C.  H.  Smyth,  Jr. 

The  ores  are  of  chief  importance  in  the  Juniata  district. 
The  belt  extends  southwestward  across  Maryland  and  eastern 
West  Virginia,  where  the  beds  are  quite  thick,  although  as  yet 
not  much  developed,  and  appears  in  the  extreme  southwest 
corner  of  Virginia.  Thence  it  runs  across  eastern  Tennessee, 
and  is  of  very  great  importance.     The  lines  of  outcrop  aje 

^  J.  H.  Dewees,  "Fossil  Ores  of  the  Juniata  Valley,"  Perm.  Geol.  Sur- 
vey, Rep.  F.  E.  d'lnvilliers,  Ibid.,  Rep.  F3  (Union,  Snyder,  Mifflin,  and 
Juniata  counties).  A.  S.  McCreath,  Ibid.,  Rep.  MM,  p.  23i.  J.  J. 
Stevenson,  Ibid.,  Reps.  MM  and  T2  (Bedford  and  Fulton  counties).  I. 
C.  White,  Ibid.,  Reps.  MM  and  T3  (Huntingdon  County) .  H.  H.  Stoek, 
"Ores  at  Danville,  Montour  County,"  Trans.  Amer.  Inst.  Min.  Eng.,  XX., 
369. 


THE  IRON  SERIES  CONTINUED, 


117 


known  as  **dyestone  ranges."  They  lie  west  of  the  Siluro-Cam- 
brian  limestones  (Example  2a)  and  in  the  edges  of  the  Cum- 
berland tableland.  Four  or  five  are  known,  of  which  the 
largest  extends  across  the  State.     This  ore  is  more  fossiliferous 


Fig.  18. — Clinton  Ore,  Eureka  Mine,  Oxmoor,  Ala.     After  C.  H.  Smyth,  Jr. 

toward  the  south  and  more  oolitic  toward  the  north.  It  is   very 
productive  in  the  Chattanooga  region.^ 

2.02.06.     The  Clinton  just  appears  in  northwestern  Georgia, 
and  continues  thence  into  Alabama,  where  it  is  again  of  great 


Fig.  19. — Cross-section  of  the  Sloss  Mine,  Red  Mountain,  Ala. 

importance,  and,  with  the  less  productive  Siluro-Cambrian 
limonites,  furnishes  practically  all  the  ore  of  the  State.  The 
outcrop  can  be  traced  almost  continuously  for  130  miles.  The 
ore  is  rich  in  fossils  and  occurs  in  several  beds, which,  although 
averaging  much  less,  may  aggregate,  as  at  the  Eureka  furnace, 
as  much  as  34  to  37  feet.     The  chief  mines  are  in  Red  Mountain, 


^  Killebrew  and  Safford,  Resources  of  Tennessee.  E.  C.  Pechin,  "The 
Iron  Ores  of  Virginia, "  etc.,  Trans.  Amer.  Inst.  Min.  Eng.,  XIX.,  1016. 
J.  B.  Porter,  "Iron  Ores,  Coal,  etc.,  in  Alabama,  Georgia,  and  Tennessee," 
Trans.  Amer.  Inst.  Min.  Eng.,  XV.,  170.  J.  M.  Safford,  Geol.  of  Tenn. 
P.  N.  Moore,  Virginias,  May,  1880,  p.  78. 


118  KEMP'S  ORE  DEPOSITS. 

a  local  name  for  the  northeast  and  southwest  ridges,  in  which 
the  ore  outcrops,  east  and  south  of  Birmingham.  Folds  and 
faults  have  brought  the  beds  into  close  proximity  with  the  coal 
and  limestone  of  the  region,  and  thus  into  a  position  very 
favorable  for  economic  working.^ 

The  accompanying  map,  Fig.  20,  illustrates  the  geography 
and  economic  geology  of  the  Birmingham  district.  In  expla- 
nation it  may  be  said  that  the  three  coal  fields,  the  Warrior, 
the  Cahaba,  and  the  Coosa,  make  three  elevated  basins,  formed 
in  part  by  synclinal  foldings  and  in  part  by  faulting.  The 
intervening  strips  are  relatively  depressed  and  constitute  the 
so-called  valleys,  each  of  which  has  its  own  name.  Thus  there 
is  a  long  valley  in  which  Birmingham  is  situated  and  which 
forks  at  the  northeast  corner  of  the  map.  The  central  portion 
of  it  consists  of  Cambrian  and  Lower  Silurian  rocks,  which 
yield  brown  hematite  ores,  as  indicated  on  the  map.  They, 
however,  are  a  miner  feature  and  do  not  form  over  10% 
of  the  total  furnace  supply.  On  each  side  of  the  valley  there 
is  a  ridge  called  Red  Mountain,  mostly  formed  by  Clinton 
strata,  with  Trenton  limestone  beneath  and  black  Devonian 
shale  above.  The  Clinton  reaches  a  thickness  of  150  feet,  but 
is  quite  variable  in  character.  It  may  contain  as  many  as  five 
or  more  beds  of  ore  of  differing  thicknesses  and  somewhat  con- 
trasted composition  and  structure.  The  best  of  these  are 
worked.  The  Clinton  beds  in  Red  Mountain  dip  on  each  side 
awaj^  from  the  center  of  the  valley,  and  really  are  the  remains 
of  an  anticline  eroded  at  its  crest.  The  anticline  is  of  the  usual 
Appalachian  type  with  steeper  dips  on  one  flank,  in  this  case 
the  northwestern,  than  on  the  other,  and  the  crest  is  nearer  the 
northwest  side  than  the  northeast.  The  dip  at  one  important 
mine  is  shown  in  Fig.  18.  The  most  productive  points  are  east 
and  south  of  Birmingham,  and  along  this  line  the  largest 
mines  are  situated.  The  ore  is  chiefly  won  hy  open  cuts,  and. 
is  laid  bare  by  stripping  off  the  banging.     Curiously  enough, 

*  A.  F.  Brainerd,  "On  the  Iron  Ores,  Fuels,  etc.,  of  Birmingham,  Ala.," 
Trans.  Amer.  Inst.  Min.  Eng.,  XVII.,  151.  "TheSloss  Iron  Ore  Mines," 
Engineering  and  Mining  Journal,  Oct.  1,  1892,  p.  318.  T.  S.  Hunt,  "Coal 
and  Iron  in  Alabama,"  Trans.  Amer.  Inst.  Min.  Eng.,  XI.,  236.  J.  B. 
Porter,  "Iron  Ores,  Coal,  etc.,  in  Alabama,  Georgia,  and  Tennessee, "  Trans. 
Amer.  Inst.  Min.  Eng.,  XV.,  170.  E.  A.  Smith,  Alabama  Geol.  Survey, 
1876;  also  Proc.  Amer.  Assoc.  Adv.  Sci.,  XXVII.,  246, 


THE  IRON  SERIES  CONTINUED. 


119 


3y 


Bangor 


V 


N*^ 


Reids 


Blount 
Sprs.  \ 


4"^ 


Jasper 


hJlUberry 


COXi. 


l^lNp 


^V^ 


Connellsville  i^^^Tvto/ ivicuaua/     /^n  6?C-;'-^Jiroo|fs 

STANDARD       V^  r-^^S^   4/ 

Milldale  1  *^>^,  X   .m^^  c,Wm^\.M-'^    O 

EUREKA/CCWf^Oj 


Fig.  20.  — 1' a?)  of  the  Vicinity  of  Birmingham,  Ala.     From  the  Transactions 
of  the  American  Institute  of  Mining  Engineers,  Vol.  XIX.,  Plate  IV. 


120  KEMP'S  ORE  DEPOSITS. 

for  an  ore  in  the  midst  of  limestone  and  limey  shales,  it  is  pre- 
vailingly siliceous,  so  that  non-siliceoua  or  calcareous  varieties 
are  much -sought- for  mixtures.  The  red  hematites  are  also 
exposed  in  Murphrees  Valley  and  are  developed  in  some  large 
and  productive  openings.  While  on  the  west  this  valley  has 
the  normal  and  anticlinal  flank,  it  is  faulted  along  the  east  so 
that  the  Clinton  measures  lie  against  the  Cambrian  shales  and 
are  overthrown  to  a  steep  northwesterly  dip. 

2.02.07,  Red  hematite,  supposed  to  be  of  the  Clinton  stage, 
occurs  in  Nova  Scotia  in  very  considerable  amount,  in  Pictou 
and  Antigonish  counties.^ 

2.02.08.  In  general  the  Clinton  ore  is  characterized  by  a 
high  percentage  of  phosphorus,  and  is  seldom,  if  ever,  available 
for  Bessemer  pig.  It  is  chiefly  employed  for  ordinary  foundry 
irons.  The  percentage  in  iron  varies  much.  Experience  at 
Clinton,  N.  Y.,  shows  that  it  averages  about  44%  Fe  in  the  fur- 
nace. These  hematites  have  undoubtedly  originated  in  some 
cases  by  the  weathering  of  ferruginous  limestones  above  the 
water  level.  I.  C.  Russell  has  shown  that  the  unaltered  lime- 
stones at  the  bottom  of  a  mine  in  Atalla,  Ala.,  250  feet  from 
the  surface,  contained  but  7.75%  Fe,  while  the  outcrop  afforded 
57.52%.  J.  B.  Porter  has  recorded  the  gradual  increase  of 
lime  also  in  another  Alabama  mine  from  a  trace  at  the  outcrop 
to  30.55%  at  135  feet.  Other  writers  have  explained  these  beds 
as  due  to  the  bringing  of  iron  in  solution  into  the  sea  of  the 
Clinton  age  and  to  its  deposition  as  small  nodules,  etc.,  or  as 
ferruginous  mud  (Roger,  Lesley,  Newberry).  In  this  way 
an  oolitic  mass  has  originated,  as  in  the  modern  Swedish  lakes 
(Newberry).  (See  Example  1. )  N.  S.  Shaler  has  argued,  on  the 
basis  of  the  Kentucky  betls,  that  the  iron  has  been  derived 
from  the  overlying  shales,  and  descending  in  solution  has  been 
precipitated  by  the  lower-lying  limestones.  As  the  shales  are 
themselves  calcareous,  this  seems  improbable.  A.  F.  Foerste 
has  shown  that  the  ore  is  very  often  deposited  either  in  the 
interstices  of  fragments  of  bryozoans  or  as  replacing  their  sub- 
stance. The  rounded,  water-worn  character  of  the  original 
fragments  is  regarded  as  occasioning  the  apparent  concretion- 
ary character.     Admirable  work  upon  the  origin  of  the  ore  has 

^  Sir  J.  W.  Dawson,  Acadian  Geology,  p.   591.     Fletcher,  Can.   Geol 
Survey,  1886. 


THE  IRON  SERIES  CONTINUED.  lt\ 

also  been  done  by  C.  H.  Smyth,  Jr.  He  finds  that  the  small 
oolites,  or  concretions,  as  they  occur  at  Clinton,  N.  Y.,  and 
many  other  localities,  have  a  water- worn  grain  of  quartz  as  a 
nucleus.  The  character  of  the  grain  is  such  that  it  has  evi- 
dently been  derived  from  granitoid  or  schistose  rocks.  The 
hematite  comes  off  at  times  in  concentric  layers,  when  tapped 
gently.  It  may  also  be  dissolved  away  so  as  to  leave  a  sili- 
ceous cast  or  skeleton  of  the  spherule.  Dr.  Smyth  thus  makes 
a  strong  argument  that  the  ores  in  such  cases  are  concretion- 
ary, and  that  they  were  formed  in  shallow  waters  around  the 
nuclei  of  sand.  But  he  also  admits,  as  others  quoted  above 
have  indicated,  that  the  replacement  of  brj'ozoa  and  the  weath- 
ering of  ferruginous  limestone  have  in  many  localities  played 
their  part.  The  iron  ore  is  in  the  latter  case  a  residual  prod- 
uct, but  now  the  mine  waters  are  depositing  calcium  carbonate 
rather  than  removing  it.^ 

2.02.09.  Glenmore  Estate,  Greenbrier  County,  West  Vir- 
ginia. A  bed  of  red  hematite  in  Oriskany  sandstones.  Limon- 
ites  are  abundant  in  the  Oriskany  of  Virginia,  and  the  hema- 
tite may  have  been  derived  from  some  such  original.^ 

2.02.10.  Mansfield  Ores,  Tioga  County,  Pennsylvania. 
Three  beds  of  ore  are  found  in  the  strata  of  the  Chemung  stage 
of  Tioga  County,  Pennsylvania.  They  are  known  as  (1)  the 
Upper  or  Spirifer  Bed,  (2)  the  Middle  or  Fish  Bed,  and  (3)  the 
Lower  Ore  Bed.  No.  1  is  full  of  shells  and  is  about  200  feet 
below  the  Catskill  red  sandstones,  and  at  Mansfield  is  two  to 
three  feet  thick.  No.  2  is  oolitic,  resembles  the  Clinton  ore, 
and  affords  fish  remains.     It  lies  about  200  feet  below  No.  1 

*  A.  F.  Foerste,  ''Clinton  Group  Fossils,  with  Special  Reference  to  Col- 
lections from  Indiana,  Tennessee,  and  Georgia,"  Amer.  Jour.  Sci.,  iii., 
XL.,  252.  (Abstract;  original  not  cited.)  "Clinton  Oolitic  Iron  Ores," 
Amer.  Jour.  Sci.,  iii.,  XLI.,  28.  Rec.  "Notes  on  Clinton  Group  Fossils, 
with  Special  Reference  to  Collections  from  Maryland,  Tennessee,  and 
Georgia,"  Proc.  Bost.  Soc.  Nat.  Hist.,  XXIV.,  263.  J.  P.  Lesley,  Iron  Man- 
ufacturers' Guide,  p.  611.  J.  S.  Newberry,  "Genesis  of  the  Ores  of  Iron," 
School  of  Mines  Quarterly,  November,  1880,  p.  13.  Rec.  H.  D.  Rogers, 
Geol  of  Penn.,  Vol.  II.,  p  127.  N.  S.  Shaler,  Geol  of  Ky.,  Vol.  III.,  p. 
163.  C.  H.  Smyth,  Jr.,  "On  the  Clinton  Iron  Ore,"  ^mer.  Jour.  Sci., 
June,  1892,  p.  487.  Rec.  "  Die  Haematite  von  Clinton  in  den  oestlichen 
Vereinigten  Stachin,"  Zeitscher.  fur  prakt.  Geologic,  1894,  304. 

"^  W.  N.  Page,  "The  Glenmore  Iron  Estate,  Greenbrier  County,  West 
Virginia,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVII.,  115. 


122  KEMP'S  ORE  DEPOSITS. 

and  varies  up  to  six  or  seven  feet  thick.  -No.  3  is  100  to  200 
foet  lower,  and  contains  small  quartz  pebbles.*  The  ore  is  not 
rich,  and  but  little  has  been  mined.  It  is  a  brownish  red  hema- 
tite.' 

2.02.11.  Beds  of  red  hematite  are  reported  by  Schmidt  in 
the  Lower  Carboniferous  of  western  central  Missouri.^ 

2.02.12.  Example  7.  Crawford  County,  Missouri.  Bodies 
of  finely  crystalline  specular  hematite,  associated  with 
chert,  sandstone  fragments,  residual  clays  and  some  pyrite 
in  conical  or  rudely  cylindrical  depressions  in  the  Cambrian 
(Ozark)  Series.  A  broad  area  of  upheaval  runs  across 
central  Missouri  from  the  east,  near  St.  Louis,  to  the  south- 
western part  of  the  State.  In  the  eastern  and  central  portions 
it  is  chiefly  composed  of  Cambrian  and  Silurian  strata,  but  to 
the  southwest  Lower  Carboniferous  come  in  (see  2.06.06).  The 
hematites  here  considered  belong  in  the  Cambrian.  In  the 
region  of  the  mines  there  is  a  heavy  sandstone  stratum,  earlier 
called  the  '* Second  Sandstone,"  but  in  the  later  reports  described 
as  the  Roubidoux.  It  is  underlain  by  a  heavy  limestone  stra- 
tum locally  called  the  Gasconade.  The  Ozark  uplift  was  formed 
at  the  close  of  the  Lower  Carboniferous  and  has  remained  exposed 
to  atmospheric  agencies  ever  since.  Their  effects  are  shown  in 
the  great  mantles  of  residual  clay,  which  are  widely  distributed, 
and  in  the  phenomena  of  the  hematite  deposits.  Dr.  A. 
Schmidt,  of  the  Missouri  Survey  of  1872  (Report  on  Iron 
Ores.  p.  QQ),  wrote  that  these  had  replaced  the  pre-existing 
rock,  or  had  been  deposited  in  hollows  in  the  then  existing  sur- 
face. Pumpelly,  however,  in  1885,*  advanced  a  more  probable 
hypothesis,  which  is  strongly  supported  by  F.  L.  Nason.  The 
region  is  and  has  long  been  one  of  sink-holes  caused  by  sub- 
terranean drainage  through  the  Gasconade  limestone  and  the 
caving  in,  at  times,  of  the  overlying  sandstone.  Cavities  were 
thus  afforded  in  which  ferruginous  waters  might  stand  and 
precipitate  their  dissolved   burden  of  ore.     Nason  shows  that 

^  A.  S.  McCreath,  Rep.  MM,  Second  Penn.  Survey,  p.  231. 

^  J.  P.  Lesley,  Geol.  of  Penn.,  1888,  Vol.  I.,  p.  311.  A.  Sherwood,  Rep. 
G,  Second  Penn.  Survey,  pp.  33,  37,  41,  42,  67.  A.  S.  McCreath,  Rep.  MM, 
Second  Penn.  Survey,  p.  251. 

^  A.  Schmidt,  "Iron  Ores  and  Coal  Fields,"  Missouri  Oeol  Survey,  1872, 
p.  169. 

*  Tenth  Cenms,  Vol.  XV. .  p.  12. 


^mii-m^^^^^^^^^'mmw^r^^m^M^^m^m.'i 


■®ca*'»^***r" 


x.'A  Z'ni-js^ 


Fig.  21.— View  in  Cherry  Valley  Mine,  showing  sandstone  with  under- 
lying cherty  clay.     The  sandstone  dips  southeast  inward 
toward  the  ores.     After  F.  L.  Nason,  Report  on 
Iron  Ores  of  Missouri,  p.  125.     Plate  VI. 


Fig.  23. — Section  of  the  northern  end  of  the  Cherry  Valley  Mine.     1,  Clay 
detritus;  2,  Sandstone;  3,  Chei'ty  and  slaty  clay;  4,  Ores;  5, 
Blocks  of  sandstone.     After  F.  L.  Nason,  Re- 
port on  Iron  Ores  of  Missouri,  p.  131. 


F'G.  23.— Cross  section  of  the  Cherry  Valley  Mine.     1.  Sandstone;  2,  Clay 

and  chert;  3,  Sandstone  dipping  inward;  4,  Magnesian 

limestone.    After  F.  L.  Nason,  Report  on  the 

Iron  Ores  of  Missouri,  p.  134. 


THE  litON  SERIES  CONTINUED.  123 

several  of  the  largest  mines  are  along  lines  of  old  drainage 
valle3^s.  The  edges  or  walls  of  the  pits  are  formed  by  the 
sandstone  which  dips  inward,  as  shown  in  the  accompanying 
figures.  Just  how  much  overlying  rock  has  washed  away 
does  not  appear  with  all  desirable  certainty,  but  the  presence 
01  large  amounts  of  chert  mixed  with  the  ore  indicates  that  the 
cap  must  have  been  to  a  great  extent  limestone  with  interbedded 
layers  of  this  rock.  As  Nason  states^  the  limestone  that  fell 
into  the  cavities  has  been  replaced  with  ore.  It  is  very  proba- 
ble that  the  former  was  an  important  precipitating  agent  to  the 
latter.  A  fossil  crinoid  was  found  at  Cherry  Valley,  replaced 
by  hematite,  giving  evidence  that  even  Lower  Carboniferous 
strata  had  been  present.  The  leaching  of  these  old,  overlying 
beds  and  the  superficial  drainage  seem  to  indicate  the  method 
of  derivation  of  the  ore. 

The  most  productive  counties  are  Crawford,  Phelps  and 
Dent,  but  smaller  deposits  occur  in  several  others.  The  largest 
mines  are  the  Cherry  Valley,  with  a  total  product  of  over  half 
a  million  tons,  the  Simmons  Mountain,  which  has  yielded 
about  half  as  much,  and  the  Meramec  with  375,000. 

The  total  product  of  all  the  mines  is  computed  by  Nason 
at  about  two  and  one-quarter  millions  of  tons.  A  sample  from 
a  stockpile  made  up  at  St.  Louis  furnaces  from  several  mines, 
yielded  Fe  56.43,  P  0.065  (Nason,  /.  c.  p.  157),  but  many  are 
much  lower  in  iron.  In  former  years  100,000  to  200,000  tons 
were  annually  produced ;  recently,  however,  much  less.  Some 
anomalous  features  are  presented  by  these  ores  in  that  they  are 
specular  hematite  in  a  practically  unmetamorphosed  sandstone, 
whereas  some  less  crystalline  form  would  naturally  be  expected. 
Nason  believes  that  they  were  originally  sulphides,  and  that 
the  heat  generated  by  the  decomposition  of  this  mineral  has 
effected  the  change  to  specular.^ 

2.02.13.  Examples.  Jefferson  County,  New  York.  Large 
buf  irregular  bodies  of  red  hematite  associated  with  crystalline 

'  "Iron  Ores  of  Missouri,"  p.  138,  Mo.  Geol.  Sur.,  1892. 

^  W.  M.  Chauvenet,  Tenth  Cenms,  Vol.  XV.,  1885,  p.  403.  F.  L.  Nason. 
"  Report  on  Iron  Ores,"  pp.  119-156,  218-231.  Missouri  Oeol.  Survey,  1892. 
Rec.  R.  Pumpelly  "On  the  Origin  of  the  Ore,"  Tenth  Census,  Vol.  XVI., 
p.  12.  Rec.  A.  Schmidt,  "Iron  Ores  and  Coal  Yields,"  Missouri  Geol. 
■Survey,  1872,  p.  124. 


124  KEMP'S  ORE  DEPOSITS. 

limestone,  serpentine,  and  pyritous  gneiss  and  overlain  by  Pots- 
dam sandstone.  The  crystalline  limestone  is  certainly  pre- 
Cambrian,  and  would  be  called  Algonkian  in  the  later  use  of 
this  term„  and  later  Laurentian  in  the  earlier  nomenclature.^ 
In  a  recently  issued  report  to  James  Hall,  State  Geologist,  C. 
H.  Smyth,  Jr.,  has  named  the  limestone  series  the  Oswe- 
gatchie.  The  ore  bodies  occur  along  a  northeast  belt,  from 
Philadelphia,  Jefferson  County,  to  Gouverneur,  St.  Lawrence 
County.  They  range  up  to  30  or  40  feet  in  thickness  and  con- 
sist of  red,  earthy  hematite  in  porous  or  cellular  masses,  with 
some  specular.  Many  interesting  minerals,  including  siderite, 
millerite,  chalcodite,  quartz,  etc.,  are  found  in  cavities,,  The 
alignment  of  the  mines  along  a  marked  belt  has  given  some 
ground  for  thinking  them  interbedded  deposits,  and  their  asso- 
ciation with  Potsdam  sandstone  has  created  the  impression  that 
they  are  of  Cambrian  (or  as  it  was  then  called,  Lower  Silu- 
rian) age.^  J=  P.  Kimball  has  stated  that  they  are  replace- 
ments of  Calcif erous  limestone.  *  E.  Emmons  in  the  * '  Report  on 
the  Second  District"  of  the  early  New  York  Survey,  regarded 
the  associated  crystalline  limestone  as  an  intruded  igneous 
mass,  and  the  same  method  of  origin  was  applied  to  the  ores 
and  accompanying  so-called  serpentine.  The  latter  was  called 
rensselaerite  by  Emmons.  Brooks  gave  the  following  section, 
taken  at  the  Caledonia  Mine:  1  Potsdam  sandstone,  40  feet. 
2.  Hematites,  40  feet.  3.  Soft,  schistose,  slaty,  green,  magne- 
sian  rock  with  pyrite  and  graphite,  90  feet  plus.  4.  Granular, 
crystalline  limestone,  with  phlogopite  and  graphite.  5.  Sand- 
stone (like  1),  15  feet.  6.  Crystalline  limestone  with  beds  and 
veins  of  granite.  C.  H.  Smyth,  Jr.,  has  recorded  the  strati - 
graphical  observations,  cited  earlier,  and  has  formulated  the 
following  explanation  of  origin.  The  lineal  arrangement  of 
the  ore-bodies  is  referred  to  their  association  with  a  great  stra- 
tum of  pyritous  gneiss  belonging  to  the  Oswegatchie  Series. 
This  weathers  deeply  and  becomes  light  and  porous  (constitut- 

*  C.  H.  Smyth,  Jr.,  "Geological  Reconnaissance  in  the  Vicinity  of 
Gouverneur,  N.  Y.,"  Trans.  N.  Y.  Acad.  Sci.,  XII.,  97,  1893.  "Report  on 
Jefferson  and  St.  Lawrence  Counties, "  i^ep.  of  N.  Y.  State  Geol.,  1893, 
493.     Also  1895,  481. 

2  See  T.  B.  Brooks,  Amer.  Jour.  Sci.,  iii.,  IV.,  22. 

^  J  P.  Kimball,  Amer.  Geologist,  December,  1891,  p.  368. 


THE  IRON  SERIES  (JuNTINUED.  125 

ing  thus  a  "fahlband").  It  coBtains  considerable  dissemi- 
nated magnetite.  The  so-called  serpentine  or  reusselaerite  only 
occurs  in  association  with  ore,  and  itself  varies  in  character, 
so  that  one  is  justified  ,  in  regarding  it  as  an  altered  form  of 
several  different  kinds  of  rocks.  Smyth  infers  that  the  decay 
of  the  ferruginous  minerals,  but  especially  of  pyrite  in  the 
pyritous  gneiss,  has  furnished  the  iron- bearing  solutions,  which 
following  down  the  dip  have  replaced  the  crystalline  limestone 
where  the  presence  of  intruded  granites  or  the  flattening  of  the 
dip  checked  the  circulations.  The  action  of  the  acidulated  fer- 
ruginous waters  has  altered  the  granites  and  gneisses  in  the 
limestone  series  to  the  so-called  serpentine.^  These  views  are 
fortified  by  microscopic  study  of  the  rocks,  and  though 
advanced  only  as  an  hypothesis  are  worthy  of  great  confidence. 

The  mines  have  afforded  in  the  past  a  moderately  rich  (50 
to  bb%  Fe),  non-Bessemer  ore.  The  best  known  and  largest 
producers  are  the  Old  Sterling,  the  Caledonia  and  Kearney 
properties,  but  they  are  not  now  operated  and  are  not  likely  to 
be  reopened  in  the  immediate  future. 

2.02.14.  Example  9.  Lake  Superior  Hematites.  Bodies 
of  hematite,  both  red  and  specular,  soft  and  hard,  anhydrous 
and  somewhat  hydrated,  associated  with  jaspers  and  cherts, 
and  deposited  by  the  replacement  of  cherty  iron  carbonate  with 
iron  oxide,  in  troughs,  formed  by  some  relatively  impervious 
rock.  The  impervious  rock  is  usually  a  decidedly  altered  igne- 
ous dike,  now  hornblendic  and  dioritic,  but  one  that  has  been 
originally  diabase.  The  trough  may  be  formed  by  a  folded  dike ; 
by  two  or  more  intersecting  dikes;  by  the  intersection  of  a  dike 
and  a  compact,  sedimentary  stratum ;  or  less  commonly  by  a 
folded  bed  of  slate.  All  of  these  varieties  are  known  in  one 
place  and  another.  Increasing  study  has  shown  that  the  paral- 
lelism in  the  structure  of  the  several  districts,  in  the  associates 
of  the  ore,  and   in  the  geological  horizons  at  which  the  ore 

/  T.  B.  Brooks,  "On  Certain  Lower  Silurian  Rocks  in  St.  Lawrence  Co., 
New  York,"  Amer.  Jour.  Sci.,  iii.,  IV.,  p.  22.  Rec.  G.  S.  Colby,  Jour 
U.  S.  Assoc.  Charcoal  Iron  Workers,  XL,  p.  263.  E.  Emmons;  iV.  Y.  Geol. 
Survey,  Second  District,  p.  93.  T.  S.  Hunt,  "  Mineralogy  of  the  Lauren- 
tian  Limestones  of  North  America,"  21st  Ann.  Rep.  Regents  N.  Y.  State 
Univ.,  1871,  p.  88.  J.  C.  Smock,  Bull.  N.  Y.  State  Mus.,  No.  7, 1889,  p.  44. 
Rec.  C.  H.  Smyth,  Jr.,  in  Report  of  N.  Y.  State  Geologist  for  1894.  and 
Journal  of  Geology,  IL,  678,  1894.     Rec. 


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THE  IRON  SERIES  CONTINUED.  127 

occurs,  is  pronounced.  Magnetite  is  at  times  present  and  limo- 
nites  have  been  mined  to  a  limited  degree.  There  are  five 
principal  ore-producing  belts  or  districts,  which  are  also  called 
in  instances** ranges,"  as  they  follow  ranges  of  low  hills.  They 
are,  in  the  order  of  their  chronological  exploitation,  the  Mar- 
quette, just  south  of  Lake  Superior,  in  Michigan;  the  Menomi- 
nee, on  the  southern  border  of  the  Upper  Peninsula  and  partly 
in  Wisconsin;  the  Gogebic  or  Penokee-Gogebic,  on  the  north- 
western border  between  Michigan  and  Wisconsin;  the  Vermil- 
ion Lake,  in  Minnesota,  northwest  of  Lake  Superior;  and  the 
Mesabi  (Mesaba),  in  the  same  general  region  as  the  last. 

2.02.15.  The  geology  of  these  districts  has  been  a  subject  of 
much  controversy,  not  alone  in  the  relations  of  the  separate 
areas,  but  in  the  subdivisions  of  a  single  one.  The  ever-pres- 
ent difficulty  of  classifying  and  correlating  metamorphic  rocks 
has  here  been  very  great.  Moreover,  there  are  other  separate 
districts,  of  related  geological  structure,  which  ought  also  to 
be  brought  into  harmony,  and  only  at  a  very  recent  date  has 
this  been  even  partially  attained. 

2.02.16.  The  ores  and  their  inclosing  rocks  have  usually 
been  called  Hurouian,  as  this  is  the  name  formerly  applied  to 
the  schistose  and  metamorphic  rocks  overlying  what  was  con- 
ceived to  be  the  basal,  gueissic  Laurentian.  The  geologists  of 
the  United  States  Geological  Survej^  have  essentially  modified 
this  nomenclature,  and  have  restricted  Archean  to  the  earliest 
crystalline  or  metamorphosed,  igneous  rocks  that  precede  the 
first  sediments.  Algonkian  is  then  employed  for  the  first  and 
subsequent  sedimentary  rocks,  and  for  the  igneous  intrusions 
that  followed  the  first  sediments  up  to  the  opening  of  the  fos- 
siliferous  Cambrian.  The  difficulty  of  correctly  correlating 
these  strata  with  the  original  Huronian  prompted  the  step,  but 
Huronian  is  still  in  very  general  use  and  Algonkian  and  the 
new  meaning  of  Archean  have  received  but  moderate  support 
outside  of  the  Survey.  In  later  years,  however,  the  excep- 
tionally difficult  geological  problems  in  the  iron  ore  districts  on 
the  south  side  of  Lake  Superior  have  been  especially  solved  by 
the  geologists  of  the  U.  S.  Survey^  Irving,  Van  Hise,  Bayley, 
H.  L.  Smyth,  and  others,  and  it  is  upon  their  work  that  the 
following  descriptions  for  the-  three  districts  in  question  are 
based.     The  references  in  the  footnote  following  will  place  any 


128  KEMP'S  ORE  DEPOSITS. 

reader  in  touch  with  the  earlier  literature,  reviews  of  which 
will  be  found  in  the  citations  from  Van  Hise,  A.  Winchell  and 
Wads  worth.  ^  The  north  shore  districts  are  also  closely  related , 
and  as  a  geological  problem  account  must  be  taken  as  well  of 
the  original  Huronian  area,  north  of  Lake  Huron,  and  of  the 
Kaministiquia  and  Rainy  Lake  regions  north  of  Lake  Supe- 
rior, although  they  contain  no  iron  ores.^ 

2.02.1?.  The  oldest  or  pre-sedimentary  rocks  (Archean) 
consist  of  massive  granites,  gneissoid  granites,  syenites,  perido- 
tites,  greenstone  schists,  and  other  schists  that  are  sheared  and 
metamorphosed  igneous  rocks  and  tuffs  of  various  kinds.  They 
were  called  the  *' Fundamental  Complex"  by  Irving,  and  the 
name  in  the  form  of  "Basement  Complex"  has  been  retained 
in  the  later  work.  Further  investigation  maj^  clear  up  its 
stratigraphical  relations  to  a  certain  extent.  The  Archean  is 
succeeded  by  the  formations  of  the  Algonkian,  which  involve 
or  succeed  undoubted  sediments.  In  the  south  shore  iron 
ranges  the  Algonkian  has  been  quite  uniformly  found  to  be 
divisible  into  two  series,  which  are  separated  by  an  unconform- 
ity and  a  considerable  period  of  erosion.  The  lower  is  called 
Lower  Huronian,  Lower  Marquette,  Keewatin,  Lower  Vermil- 
ion, and  Menominee  proper  in  the  different  exposures,  and  prob- 
ably the  great  cherty  limestone  of  the  Penokee-Gogebic  series 
is  its  local  equivalent.  In  the  Marquette  district  Wadsworth 
has  recently  divided  it  still  further  into  the  Republic  and  Mes- 
nard  formations.  The  upper  part  follows  an  unconformity  and 
is  called  in  the  different  regions  L^pper  Huronian,  Animikie, 
Upper  Vermilion,  Upper  Marquette,  Western  Menominee,  and 

*  C.  R.  Van  Hise,  "An  Attempt  to  Harmonize  Some  Apparently  Con- 
flicting Views  on  Lake  Superior  Stratigraphy,  Amer.  Jour.  Sci.,  ii.,  XLI., 
117;  Tenth  Annual  Report  Director  U.  S.  Geol.  Survey.  Van  Hise, 
Bayley  and  Smyth,  Monograph  XXVIII.  of  U.  S.  Geological  Survey  on 
the  Geology  of  the  Marquette  Iron  District.  A.  Winchell,  ' '  A  Last  Word 
with  the  Huronian,"  Bull.  Geol.  Soc.  Amcr.,  XL,  85.  M.  E.  Wadsworth, 
"  Notes  on  the  Geology  of  the  Iron  and  Coi)per  Districts,"  1880. 

^  The  following  papers  deal  with  the  ores  in  general:  D.  N.  Bacon,  "The 
Development  of  Lake  Superior  Iron  Ores,"  Trans.  Amer.  Inst.  Min.  Eng., 
XXVII.,  841;  John  Birkinbine,  "The  Resources  of  the  Lake  Superior 
Region,"  Idem,  XVL,  168,  1887;  "The  Iron  Ore  Supply,"  Idem,  XXVIL, 
519:  H.  V.  Winchell,  "Historical  Sketch  of  the  Discovery  of  Mineral  De- 
posits in  the  Lake  Superior  Basin,"  Proc.  Lake  Superiar  Min.  Inst.,  IL, 
contains  a  bibliography.     See  also  Amer.  Geologist,  XIII. ,  164. 


THE  IRON  SERIES  CONTINUED. 


129 


Penokee-Gogebic  proper.  For  the  Marquette  region  this  has 
also  been  further  divided  by  Wadsworth  into  two,  the  Holj'oke 
and  the  Negaunee  formations.  It  is  much  less  metamorphosed 
than  the  lower  member,  and  in  the  Marquette  district  contains 
some  ore.  In  the  Menominee  region  of  Wisconsin  it  affords 
the  deposits  there  wrought  and  carries  the  ore  in  the  Gogebic 
range.  Higher  in  the  section,  after  another  unconformity  fol- 
lows the  Keweenawan  (Keweenian)  or  Nipigon.  This  closes 
the  Algonkian.  Still  above  is  the  Cambrian  (Eastern,  West- 
ern or  Potsdam)  sandstone. 

2.02.18.     Example  9a.     Marquette  District.    The  Marquette 


Fig.  25. — Oeneralized  section  across  the  Marquette  Iron  Range,  to  illustrate  the 
type  of  folds.     After  C.  R.  Van  Rise,  Fifteenth  Ann.  Rep. 
Dir.  U.  8.  Geological  Survey,  p.  485. 


district  was  earliest  known  and  has  been  most  thoroughly  stud- 
ied ;  but  owing  to  the  confused  geological  structure,  there  has 
been,  as  already  remarked,  much  discordance  of  interpretation. 
The  remarkably  careful  and  systematic  work  of  Van  Hise  and 
Bayley^  has,  however,  cleared  up  the  greatest  difficulties.  In 
the  Marquette  district  the  Algonkian  (or  Huronian)  rocks  form 
a  synclinorium  or  synclinal  trough,  resting  in  the  older  Archean 
crystallines  and  extending  from  Marquette  on  Lake  Superior, 
westward  in  a  nearly  east  and  west  line.  While  the  axis  of  the 
main  syncline  runs  east  and  west,  there  are  many  minor  folds 
parallel  with  this,  which  are  overturned  outwardly  from  the 

'  C.  R.  Van  Hise  and  W.  S.  Bay  ley,  "Preliminary  Report  on  the 
Marquette  Iron-bearing  District  of  Michigan,"  with  a  Chapter  on  the 
Republic  Trough,  by  H.  L.  Smyth,  Fifteenth  Annual  Report  Director  U.  S. 
Geol.  Survey,  485-650.  This  report  should  be  in  the  hands  of  every  one 
interested  in  the  region.  See  also  Monograph  XXVIII.,  which  with  its 
atlas  is  the  fullest  exposition  of  the  subject. 


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132  KEMP'S  ORE  DEPOSITS. 

ceDter  as  in  the  accompanyiDg  figure,  after  Van  Hise.  Some 
marked  folding  has  also  occurred  at  right  angles  to  the  east 
and  west  axis.  Faulting  is  almost  entirely  lacking,  and  the 
topographic  relief  is  quite  entirely  due  to  the  relative  resist- 
ances presented  by  the  several  rocks  to  erosion.  Al]  are  more 
or  less  metamorphosed  and  have  evidently  suffered  severely 
from  pressure  and  shearing  stresses.  The  Lower  Marquette  is 
chiefly  developed  at  the  eastern  end  and  around  the  rims  of  the 
synclinorium,  as  it  was  from  this  end  that  the  shore-line  seems 
to  have  advanced  upon  the  ancient  land.  It  begins  with  the 
Mesnard  quartzite,  110  to  6  70  feet  thick.  Above  come  in  order 
the  Kona  dolomite,  42^  to  1,375  feet;  the  Wewe  slate,  550  to 
1,050  feet;  the  Ajibik  quartzite,  700  to  900  feet;  the  Siamo 
slate,  200  to  625  feet;  and  the  Negaunee  iron  formation,  1,000 
to  1,500  feet.  In  Figs.  26  and  27  all  these  except  the  Negaunee 
are  grouped  under  one  sign.  The  total  thickness  varies  from 
2,975  to  6,120.  The  Upper  Marquette  includes  from  below 
upward,  the  Ishpeming  formation,  including  the  Goodrich 
quartzite  and  the  Bijiki  schist;  the  Michigamme  formation 
of  slates  and  mica  schist;  and  the  Clarksburg  formation  of 
more  or  less  altered  volcanic  rocks.  Upon  Figs.  26  and  27 
the  Ishpeming  has  one  sign  and  the  Michigamme  and 
Clarksburg  another.  In  the  mining  district  the  total  thick- 
ness of  the  Upper  Marquette  is  less  than  5,000  feet.  Except 
as  regards  the  Goodrich  quartzite  of  the  Ishpeming  and  some 
small  limonite  deposits  in  the  Michigamme  formation  the 
divisions  have  no  economic  importance.  In  the  Lower 
Marquette  the  economic  interest  centers  in  the  Negaunee 
formation,  which  is  much  the  most  important  of  alL  Later 
than  all  these  just  cited  are  intrusions  of  basic  dikes  that  have 
been  prime  factors  in  the  ore  deposition. 

The  Negaunee  formation  in  its  completest  section  consists 
from  below  upward  of  sideritic  slate  and  griinerite-magnetite^ 
slate;  ferruginous  slate;  ferruginous  chert ;  and  at  the  top  of 
jasperite  or  jasper- rock;  but  not  all  of  these  are  necessarily 
present  in  any  one  section.  The  ores  are  either  "soft  ores"  or 
*' hard  ores."  The  former  are  blue,  red  or  brown,  earthy  and 
somewhat  hydrated  varieties  of  hematite,  and  resemble  ordi- 

*  Griinerite  is  a  variety  of  amphibole  or  hornblende.  It  is  an  iron 
amphibole. 


¥ 
¥ 


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/ 


Fig.  29. — Open  cut  in  the  Republic  mine,  Marquette  range,   showing  a. 
horse  of  jasper.     From  a  photograph  hy  H.  A.  Wheeler. 


THE  IRON  SERIES  CONTINUED. 


133 


nary  dirt  of  these  colors,  with  small  lumps  of  ore  scattered 
throughout.  They  strongly  simulate,  limonite  but  are  not 
so  hydrated.  The  soft  ores  are  now  the  main  object  of 
mining,  but  they  were  earlier  looked  upon  with  disfavor 
and  only  the  hard  ores  were  sought.     The  hard  ores  are  mas- 


FlG.  28. — Cross-ftections   to  illustrate  the  occurrence  and  asfonations  of 

iron  ore  in  the  Marquette  district,  Michigan.     After  0.  E.  Van  Rise, 

Amer.  Jour.  Sci.,  Febrvary,  1892;  Engineering  and  Mining 

Journal,  July  9,  1892. 

sive  or  micaceous  specular  hematite,  rarely  magnetite,  and  are 
blasted  out  in  lumps.  Van  Hise  makes  three  classes  of  depos- 
its: (1)  Thoseat  the  bottom  of  the  iron- bearing  formation;  (2) 
those  within  it;  and  (3)  those  at  its  top,  including  also  some 
that  run  up  into  the  Goodrich  quartzite,  the  lowest  stratum  of 


134  KEMP'S  ORE  DEPOSITS. 

the  overlying  Ishpeming  formation.  The  hard  ores  belong 
to  the  third  class.  All  these  classes  rest  upon  an  impervious 
rock  of  some  sort,  and  lie  in  a  pitching  trough  formed  by  it. 
The  trough  may  be  a  fold  in  the  Siamo  slate,  and  often  is  for 
ores  of  the  first  class.  It  may  be  a  single  folded  dike,  v^^hich 
is  an  altered  diabase,  now  called  soapstone  or  paint-rock  by  the 
miners.  These  are  shown  in  the  cuts  of  Fig.  28.  The  trough 
may  result  from  the  intersection  of  two  or  rnore  dikes,  as  is 
more  fully  illustrated  under  the  Vermilion  district.  In  all 
cases  it  seems  evident  that  after  the  close  of  the  time-period  rep- 
resented by  the  Upper  Marquette,  and  after  the  intrusion  of  the 
basic  dikes,  the  overlying  ferruginous  rocks  were  subjected  to 
extensive  leaching  of  their  iron,  by  descending  atmospheric 
waters,  charged  with  carbonic  acid.  When  these  came  to  rest 
in  the  troughs,  or  met  other  descending  currents,  which  were 
charged  with  oxygen,  and  which  had  percolated  downward 
along  the  dikes,  the  dissolved  proto-salt  of  iron  was  oxidized 
and  precipitated  as  ferric  oxide,  replacing  the  cherts  or  other 
siliceous  rock  that  had  previously  filled  the  trough.  The  sil- 
ica is  thought  to  have  been  in  large  part  removed  by  alkaline 
solutions  emanating  from  the  diabase.  These  changes  were 
facilitated  by  the  fact  that  the  brittle  cherts  had  been  much 
shattered  during  the  folding,  and  this  condition  contributed  to 
the  formation  of  the  soft  ores  in  their  fragmental  condition. 
The  hard  ores  appear  to  owe  their  condition  to  the  dynamic 
metamorphism  that  has  been  particularly  strong  along  the  con- 
tact line  of  the  Upper  and  Lower  Marquette.  The  micaceous 
ores  certainly  owe  their  structure  to  shearing.  The  magne- 
tites are  supposed  to  be  former  hematites,  that  have  suffered 
partial  reduction  \yy  infiltrating  solutions  charged  with  organic 
matter.  They  are  best  developed  in  the  Republic  tongue  of  the 
main  trough. 

2.02.21.  The  origin  of  these  ore  bodies  has  been  a  subject 
of  much  controversy.  A  review  of  the  various  hypotheses  up 
to  1880  is  given  in  Wadsworth's  monograph^  and  a  still  later 
one  is  given  in  the  monograph  of  Van  Hise,Bayley  and  Smyth.  ^ 

*  M.  E.  Wadsworth,  "Notes  on  the  Iron  and  Copper  Districts  of  Lake 
Superior,"  Bull.  Mus.  Comp.  Zool.,  Vol.  VII.,  No.  1.  July,  1880. 

"  Van  Hise,  Bay  ley  and  Smyth,  "The  Marquette  Iron-bearing  District 
of  Michigan,"  Monograph  XXVIII.  U.  S.  Geological  Survey,  pp.  3-148. 
1897. 


THE  IRON  SERIE8  CONTINUED.  135 

The  early  survey  of  Foster  and  Whitney  (1851)  attributed  an 
eruptive  origin  to  them  and  the  same  difficult  thesis  has  been 
supported  by  Wadsworth  (1880).  Others  formerly  regarded 
them  as  old  limonite  beds  in  a  sedimentary  series  that  was 
subsequently  metamorphosed.  Credner  (1869),  Brooks  (1873), 
and  others  saw  reason  for  it;  but  there  is  little  doubt  that 
the  origin  outlined  above  is  correct.  While  the  present  text 
follows  the  recent  work  of  the  U.  S.  Geological  Survey,  be- 
cause it  is  more  detailed,  comprehensive  and  really  accurate 
than  any  other  available,  and  because  space  is  necessarily 
limited,  yet  the  reader  who  would  thoroughly  acquaint  him- 
self with  the  questions  under  discussion  should  consult  the 
citations  given  below,  especially  those  from  Brooks,  Irving, 
Wadsworth  and  Rominger. 

2.02.22.  It  was  in  the  forties  that  the  importance  and  extent 
of  the  ore  bodies  were  first  vaguely  suspected.  The  trouble 
that  they  made  with  the  compasses  of  the  early  land  surveyors 
indicated  their  existence.  Important  mining  began  in  1854. 
Somewhat  over  100,000  tons  were  produced  in  1860,  over  800,- 
000  in  1870,  nearly  1,500,000  in  1880.  In  1877  the  Menominee 
region  was  opened,  and  in  1885  the  Penokee-Gogebic  and  Ver- 
milion districts  began  to  ship.  The  total  shipments  from  the 
Lake  Superior  region  in  1890  were  8,982,531  tons.  The  total 
production  through  1897  of  the  Marquette  district  was  49,253,- 
222  tons.  A  quite  complete  citation  of  the  literature  is  to  be 
found  in  Wadsworth's  monograph,  already  referred  to;  in  Irv- 
ing's  *' Copper-bearing  Rocks  of  Lake  Superior,"  Monograph 
v.,  U.  S.  Geol.  Survey;  and  in  Van  Hise,  Bay  ley  and 
Smyth,  Monograph  XXVIII.  See  also  under  Examples  9b,  9c, 
and  9d.  Only  the  most  important  or  most  recent  papers  are 
mentioned  here.^ 

*  J.  Birkinbine,  "Resources  of  the  Lake  Superior  District,"  M.  E.,  July. 
1887.  T.  B.  Brooks,  Oeol  Survey  of  Michigan,  Vol.  I.,  1878;  Geol.  Survey 
of  Wisconsin,  Vol.  III.,  p.  450.  H.  Credner,  "Die  vorsilurischen  Gebilde 
der  oberen  Halbinsel  von  Michigan  in  Nord  Amerika,"  Zeitsch.  d.  d.  Geol 
Ges.,  1869,  XXI..  516;  also  Berg- und  HiXtt.  Zeit.,  1871,  p.  369.  Foster 
and  Whitney,  Geol.  of  the  Lake  Superior  District,  Vol.  I.,  "Iron  Lands." 
1851.  R.  D.  Irving,  "  On  the  Origin  of  the  Ferruginous  Schists  and  Iron 
Ores  of  the  Lake  Superior  Region,"  ^7?ier.  Jour.  Sci.,  iii.,  XXXIL,  263; 
''Preliminary  Paper  on  an  Investigation  of  the  Archean  of  the  North- 
western States,"   Fifth  Ann.  Rep.  Director   U.   S.  Geol.  Survey,  p.   131; 


136  K..MP'S  ORE  DEPOSITS. 

2.02.23.  Example  96.  Menominee  District.  The  Menomi- 
nee River,  which  gives  the  district  its  name,  forms  the  south- 
easterly boundary  between  the  Upper  Peumsula  of  Michigan 
and  Wisconsin.  The  mines  are  situated  about  forty  miles 
south  of  the  Marquette  group,  and  the  same  distance  west  of 
Lake  Michigan.  The  larger  number  are  in  Michigan,  but  the 
productive  bolt  extends  also  into  Wisconsin.  They  lie  along  the 
south  side  of  an  east  and  west  range  of  hills,  which  rises  from 
200  to  300  feet  above  the  surrounding  swampy  land.  Begin- 
ning with  the  base  and  included  in  the  lower  Menominee  accord- 
ing to  H.  L.  Smj^th,  the  geological  section  is  as  follows,  all  of 

Seventh  Ann.  Rep.,  p.  431;  also  Administrative  Reports  in  subsequent 
volumes.  J.  E.  Jopling,  "The  Marquette  Range:  Its  Discovery,  Devel- 
opment, and  Resources,"  Titans.  Amer.  Inst.  Min.  Eng.,  XXVII.,  541. 
J.  P.  Kimball,  "The  Iron  Ore  of  the  Marquette  District,"  Amei\  Jour,  of 
Sci.,  ii.,  XXXIX.,  290.  H.  S.  Munroe,  School  of  Mines  Quarterly,  II.,  p. 
43.  E.  Reyer,  "  Geologie  der  Anierikanischen  Eisenerzlagerstatten  (insbe- 
sonden  Michigan)."  Oest.  Zeitsch.  f.  Berg-  u.  Hutt.,  Vol.  XXXV.,  pp.  120, 
181,  1887.  C.  Rominger,  Geol.  Survey  of  Michigan,  Vol.  IV.,  1884.  "Re- 
port on  the  Iron  and  Copper  Regions,  1881-84,  Idem,  Vol.  V.,  1895.  C.  R. 
Van  Hise,  "An  Attempt  to  Harmonize  Some  Apparently  Conflicting  Views 
of  Lake  Superior  Stratigraphy,"  Ainer.  Jour.  Sci.,  iii.,  XLI.,  p.  117,  Feb- 
ruary, 1891 ;  Tenth  Ann.  Rep.  Director  U.  S.  Geol.  Survey ;  '  The  Iron 
Ores  of  the  Marquette  District  of  Michigan,"  Amer.  Jour.  Sci.,  February, 
1892,  p.  115.  15th  Annual  Report  Director  U.  S.  Geol.  Survey,  pp.  485- 
657.  Van  Hise,  Bayley  and  Smyth.  "  The  Marquette  Iron-bearing  District 
of  Michigan,"  Mono.  XXVIII.  and  Atlas  U.  S.  Geol.  Survey.  M.  E. 
Wadsworth,  • '  Notes  on  the  Iron  and  Copper  Districts  of  Lake  Superior, " 
Bull.  Mus.  Comp.  Zool.,  VIL,  1,  1880;  "On  the  Origin  of  the  Iron  Ores  of 
the  Marquette  District,  Lake  Superior,"  Proc.  Bost.  Soc.  Nat.  Hist.,  Vol. 
XX.,  p.  470;  Engineering  and  Mining  Journal,  Oct.  29,  1881,  p.  286;  Ann. 
Rep.  Mich.  State  Geologist,  1891-92.  "The  Geology  of  the  Lake  Superior 
Region,"  in  a  pamphlet  issued  by  the  Duluth,  South  Shore  &  Atlantic 
R.  R.,  1892.  Dr.  Wadsworth  announces  a  new  subdivision  of  Formations 
in  this  and  in  Amer.  Jour.  Sci.,  January.  1893,  p.  73.  H.  Wedding, 
Zeitsch.  f.  Berg-,  Hiitt-,  und  Salinemvesen  in  Preus.  Staat. ,  XXIV. ,  p.  339. 
C.  E.  Wright  and  C.  D.  Lawton,  Reps,  of  the  Commissioners  of  Mineral 
Statistics  of  Michigan,  1880,  and  annually  to  date.  G.  H.  Williams, 
' '  Greenstone  Schist  Areas  of  the  Menominee  and  Marquette  Regions  of 
Michigan,"  introduction  by  R.  D.  Irving,  Bull.  63,  U.  S.  Geol.  Survey. 
H.  V.  Winchell,  "Historical  Sketch  of  the  Discovery  of  Mineral  Deposits 
in  the  Lake  Superior  Region,  Proc.  Lake  Superior  Mining  Inst.,  II.  3. 

A  careful  compilation  of  analyses  of  ores  from  all  the  larger  mines  of 
the  four  older  ranges  is  given  by  Geo.W.  Goetz,  Trans.  Amer.  Inst.  Min. 
Eng.,  XIX.,  59,  1890. 


THE  IRON  SERIES  CONTINUED. 


137 


which  rests  on  the  Archean  crystallines:  1.  A  basal  quartzite, 
rarely  conglomeratic,  1,000  feet  thick  as  a  maximum,  and  at 
least  700  feet  over  wide  areas.  2.  A  crystalline  limestone,  700 
to  1,000  feet  thick,  and  possibly  reaching  1,500  to  2,000  on  the 
Fence  River.  This  was  earlier  called  by  Rominger  the  Norway 
limestone.  3.  Red,  black  and  green  slates  that  are  not  known  to 
exceed  200  to  300  feet.  The  slates  here  and  there  contain  the  iron 
formation  that  affords  the  rich  ores  of  Iron  Mountain  and  Nor- 
way. In  the  southern  portion  the  horizon  of  the  slates  is  in 
part  occupied  by  altered  eruptives,  which  may  thicken  up  to 
2,000  feet  on  the  Fence  River.  4.  .  The  Michigamme  jasper,  a 
greatly  altered  ferruginous  rock,  usually  carrying  apparently 


Fig.  30. — Plan   of  the  Ludington  ore  body,  Menominee   district,  Michigan. 
After  P.  Larsson,  Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  119. 

fragmental  quartz  grains.  The  rock  is  best  developed  at  Michi- 
gamme Mountain,  S.  4,  T.  43  N.,  R.  31  W.  It  is  variable  but 
appears  to  have  originally  been,  in  part  at  least,  a  clastic  sedi- 
ment. Infiltrating  iron  salts  and  the  formation  of  cherty  sil- 
ica have  brought  about  the  alteration  of  the  rock. 

Iron  ores  are  met  at  three  horizons  in  this  section.  The  low- 
est is  in  the  quartzite,  No.  1,  not  far  from  its  junction  with  the 
limestone.  It  has  yielded  but  one  workable  deposit  The 
great  majority  of  the  ore  bodies  is  in  the  slates,  No.  3.  They 
occur  as  local  concentrations  in  a  ferruginous  rock  composed 
of  banded  jasper  and  iron  ore.  The  ferruginous  rock  is  met  at 
various  horizons  in  the  slates.  The  third  ore-bearing  forma- 
tion is  the  Michigamme  jasper,  but  the  ore  bodies  are  small. ^ 

*  The  above  is  condensed  from  H.  L.  Smyth,  "Relations  of  the  Lower 
Menominee  and  Lower  Marquette  Series  in  Michigan  (Preliminary)," 
Amer.  Jour  Sci. ,  March,  1894,  216.    Further  correlative  notes  are  given  in 


138  KEMP'S  ORE  DEPOSITS. 

The  Michigamme  jasper  is  correlated  by  Smyth  with  the 
Negaunee  formation  of  the  Marquette  district,  and  this  brings 
the  principal  ore  bearing  stratum  of  the  Menominee  range 
below  the  ore-bearing  formations  in  the  Marquette. 

In  the  black  slates  of  the  Upf)er  or  Western  Menominee 
there  are  still  other  ore  bodies,  such  as  those  of  the  Common- 
wealth and  Florence  mines,  and  at  the  Quinnesec  mines.  A 
goodly  mass  of  soft  blue  ore  was  obtained  in  the  Potsdam  sand- 
stone, which  had  evidently  been  eroded  from  the  older  ores 
during  the  deposition  of  the  Potsdam.  Great  geologic  interest 
has  been  felt  in  the  metamorphism  of  the  eruptive  rocks  in  the 
Menominee  district,  and  although  remotely  related  to  the 
geology  of  the  ores,  attention  should  be  directed  to  the  valua- 
ble paper  of  G.  H.  Williams  cited  below. 

Since  1890  W.  S.  Gresley  of  Erie,  Pa.,  has  been  collecting 
from  the  ore  piles  in  that  city  most  extraordinary  slabs  of  ore, 
chiefly  from  the  Chapin  mine,  of  the  Menominee  range,  that 
contain  impressions  bearing  the  closest  resemblance  to  algse, 
or  other  low  forms  of  plant  life.  They  may  be  the  long-sought 
fossils  of  Huronian  times.  ^ 

The  Menominee  ores  are  generally  soft,  blue-earthy  hema- 
tites, which  give  a  red  powder  and  consist  of  finely  divided 
particles  of  specular.  Brown  hematites  are  very  limited.  A 
lenticular  shape  is  more  pronounced  than  in  the  Marquette 
district  and  the  concentration  of  the  ore  has  not  been  shown  to 
be  connected  with  intruded  dikes  as  elsewhere,  although  the 
chemical  reactions  involved  are  doubtless  the  same.  The  gen- 
eral strike  is  about  N.  75°  W.,  and  the  dip  70°  to  80°  N.  They 
also  pitch  diagonally  down  on  the  dip.  (Of.  New  Jersey  Mag- 
netites, Example  Vdd.)  There  has  been  produced  including  1897 
a  grand  total  of  24,931,441  tons  since  mining  began. ^ 

C.  R.  Van  Hise's  paper  on  the  Marquette  range,  in  15th  Ann.  Rep.  Dir.  U.  S. 
Geol.  Survey,  p.  647.  Smyth  has  also  given  an  excellent  short  sketch  at 
the  close  of  his  paper  on  "Magnetic  Observations  in  Geological  Mapping," 
Trans.  Amer.  Inst.  Min.  Eng.,  XXVI.,  640-709,  1896. 

^  W.  S.  Gresley,  "Traces  of  Organic  Remains  from  the  Huronian  (?) 
Series  at  Iron  Mountain,  Mich.,"  etc.,  Trans.  Amer.  Inst.  Min.  Eng., 
XXVI. ,  527.  See  also  Science,  April  24, 1896,  522 ;  Amer.  Geologist,  August, 
1896,  123. 

""  T.  B.  Brooks,  Geol.  Survey  of  Wisconsin,  Vol.  III.,  430-663.  D.  H. 
Brown,  "  Distribution  of  Phosphorus  in  the  Ludington  Mine, "  M.  E.,  XVI. 


THE  IRON  SERIES  CONTINUED.  139 

Some  fifteen  miles  north  of  the  Menominee  range,  and 
between  it  and  Negaunee  in  the  Marquette  range,  is  a  narrow, 
closely  folded  syncline,  called  the  Felch  Mountain  district.  It 
contains  a  series  of  strata  closely  parallel  to  the  Lower  Menomi- 
nee, and  apparently  an  outlier  cut  off  by  erosion.  H.  L. 
Smyth  has  also  traced  out  by  means  of  magnetic  observations 
a  northwesterly  extension  of  the  Menominee  range,  in  a  drift- 
covered  district,  so  as  almost  to  connect  with  the  Marquette 
area  west  of  the  Republic  trough.  From  20  to  30  miles  of  con- 
cealed rocks  have  thus  been  shown  that  may  prove  productive, 
although  the  cheap  ores  of  the  Mesabi  range  have  made  their 
immediate  future  uncertain.^ 

2.02.24.  Example  9c.  Penpkee-Gogebic  District.  This  lies 
in  an  east  and  west  range  of  hills  which  crosses  the  westerly 
boundary  of  the  Upper  Peninsula  and  Wisconsin,  and  is  from 
ten  to  twenty  miles  south  of  Lake  Superior,  and  eighty  to  one 
hundred  miles  west  of  the  Marquette  mines.  The  rocks  are  less 
metamorphosed  than  in  the  previous  two  districts.  The  strata 
Tun  east  and  west  with  a  northerly  dip  of  60°  to  80°  (65°  in  the 
larger  mines),  and  with  no  subordinate  folds.  The  geological 
series  is  now  generally  called  the  Penokee,  following  the  usage 
of  Irving  and  Van  Hise,  to  whose  labors  we  owe  our  accurate 
knowledge  of  the  district  and  from  whose  papers  the  following 
is  taken.  It  rests  upon  the  southern  complex  of  Archean  crys- 
tallines and  forms  a  narrow  belt,  over  70  miles  long,  and  from 
half  a  mile  to  three  miles  broad.  The  geological  structure  and 
relations  are  much  simpler  than  in  the  other  districts,  and  have 
afforded  the  key  for  the  solution  of  problems  elsewhere.  The 
strata  are  divided  into  an  upper  and  a  lower  series,  of  which 
the  former  is  much  the  larger  in  amount,  but  the  latter  is  the 

525.  J.  Fulton,  "Mode  of  Deposition  of  the  Iron  Ores  of  the  Menominee 
Range,  Michigan,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  525.  N.  P.  Hulst, 
"The  Geology  of  that  Portion  of  the  Menominee  Range  East  of  the  Me- 
nominee River,  Proc.  Lake  Superior  Mining  Institute,  March,  1893,  p.  19. 
Per  Larsson,  "  The  Chapin  Mine, "  Trans.  Amer.  Inst.  Min.  Eng.,  XVI., 
119.  C.  E.  Wright,  Geol  Survey  Wisconsin,  III.  ,666-734.  G.  H.  Williams, 
"  Greenstone  Schist  Areas  of  the  Menominee  and  Marquette  Regions  of 
Michigan,  with  an  Introduction  by  R.  D.  Irving,"  Bull.  62,  U.  S.  Oeol. 
Survey. 

'  H.  L.  Smyth,  "Magnetic  Observations  in  Geological  Mapping."  Trans, 
Amer.  Inst.  Min.  Eng.,  XXVI.,  640.  189  6. 


THE  IRON  SElilES  CONTINUED.  J41 

one  that  is  of  economic  importance.  At  the  base  is  a  cherty 
(lolomitic  limestone  300  feet  and  less  thick.  It  outcrops  chief!}" 
at  the  extreme  west  and  the  extreme  east,  and  has  no  immedi- 
ate connection  with  the  ores.  Over  this  lies  a  quartz-slate  or 
quartzite  that  is  extremely  persistent  throughout  the  entire 
area.  It  is  500  feet  and  less  thick,  and  forms  the  usual  foot- 
wall  of  the  large  ore  bodies.  Above  the  quartz  slate  is  the 
iron-bearing  member,  800  to  1,000  feet  thick.  It  is  not  clastic, 
but  consists  of  cherty  carbonates  of  iron,  with  some  magnesium 
and  calcium,  or  of  derivatives  from  these  carbonates  and  cherts. 
Three  types  of  rock  have  been  established:  (1)  The  slaty  and 
often  cherty  iron  carbonate,  more  or  less  analogous  to  siliceous 
iron  carbonates  in  the  Carboniferous  and  other  later  systems. 
It  is  regarded  as  of  organic  origin.  (2)  Ferruginous  slates 
and  cherts.  The  iron  of  the  siderite  in  type  one  has  been 
more  or  less  moved  and  redeposited  as  oxides,  and  rearrange- 
ment and  recrystallization  of  the  silica  have  also  transpired. 
(3)  Actinolite  and  magnetite  schists  have  resulted  by  the 
change  of  much  of  the  iron  carbonate  to  magnetite  and  by  the 
combination  of  the  remainder  with  lime,  magnesia  and  silica 
to  yield  actinolite.  This  last-named  type  is  especially  abun- 
dant west  of  Tyler's  Fork,  i.e.^  in  the  western  third  and  beyond 
the  productive  mining  region.  The  upper  Penokee  consists  of 
slate,  with  quartzites,  graywackes  and  schists,  12,800  feet 
thick  and  less.  It  has  no  connection  with  the  ores,  and  is  suc- 
ceeded by  the  Keweenawan  traps  and  sandstones  on  the  north. 
All  the  Penokee  strata  are  cut  by  dikes  and  sheets  of  diabase, 
some  of  which  in  the  iron-bearing  formation  have  plaj^ed  an 
important  part  in  the  production  of  the  ore  bodies. 

The  ores  are  found  in  the  lower  portion  of  the  iron-bearing 
member,  and  either  on  or  near  the  underlying  quartz-slate. 
The  northerly  dipping  quartz-slate  with  the  overlying  cherty 
carbonates  and  ferruginous  slates  is  cut  by  southerly  dipping 
diabase  dikes,  so  as  to  form  a  trough  with  sides  nearly  at  right 
angles.  The  troughs  themselves  pitch  downward  to  the  west, 
and  in  them,  as  illustrated  by  the  accompanying  figures  (Figs. 
32  and  33)  are  found  the  ore  bodies.  The  ores  are  soft  blue, 
brown  and  black  earthy  hematites,  and  often  contain  notable 
percentages  of  manganese.  There  is  little  doubt  that  they  have 
been  derived  from  the  cherty  carbonates  in  the  overlying  iron- 


142 


KEMP'S  ORE  DEPOSITS. 


1^ 

_J 

Ul 

c^i^^;' 

> 

A>-;i-j 

< 

o 

THE  IRON  SERIES  CONTINUED 


143 


bearing  formation,  which  in  the  long  run  of  weathering  and 
erosion  has  yielded  its  iron  oxide  to  descending  atmospheric 
waters,  more  or  less  charged  with  carbonic  acid.  The  iron- 
bearing  solutions  filtering  downward  have  come  to  comparative 
rest  in  the  troughs,  where  they  have  met  other  waters,  presumablj^ 
charged  with  oxygen.  The  iron  oxide  has  been  precipitated  and 
at  the  same  time  the  silica  has  been  removed  by  carbonated  waters 
or  by  those  which  have  been  rendered  alkaline  by  the  leaching  of 
the  neighboring  dikes.  The  latter  are  excessively  alterec^and 
are  locally  called  soapstone  or  soap-rock  in  description  of  their 
condition.     It  is  impossible  to  state  how  much  of  the  iron-bear- 


FlGo  SS.—Cross-section  of  the  Colby  mine,  Penokee-Gogebic  district,  Mich- 
igan, to  illustrate  occurrences  and  origin  of  the  ore.     After  C.  R. 
Van  Hise,  Amer.  Jour.  Sci.,  January,  1891. 

ing  formation  has  disappeared  in  the  protracted  process  of  super- 
ficial erosion,  but  probably  some  thousands  of  feet.  The  depth 
to  which  the  ore  will  be  found  in  the  troughs  is  also  problemati- 
cal. It  is  now  known  to  extend  to  800  feet  on  the  dip.  The 
solution  of  the  question  of  the  origin  of  these  ores  has  been 
one  of  the  most  valuable  of  the  additions  to  our  knowledge  in 
recent  years,  and  has  proved  suggestive  and  fruitful  for  all  the 
other  Lake  Superior  districts. 

The  range  became   productive  in  1885,  and  including  1897 
there  has  been  shipped  a  total  of  23,047,023  tons  of  ore.^ 

^  C.  M.  Boas,      Some  Dike  Features  of  the  Gogebic  Iron  Range,"  Trans. 
Amer.  Inst.  Min.  Eng.,  XXVIL,  556      R.  D.  Irving,  Geol.  Survey  of  Wis- 


144  KEMP'S  ORE  DEPOSITS. 

2.02.25.  Example  9d.  Vermilion  Range,  Minnesota. 
Bodies  of  hard  specular  ores  at  Vermilion  Lake,  and  soft  ores 
at  Ely,  deposited  in  troughs  as  in  the  preceding  examples, 
formed  by  folded  or  intersecting  dikes,  which  penetrate  the 
iron- bearing  formation.  The  district  is  situated  in  north- 
eastern Minnesota,  and  lies  northwest  from  Lake  Superior.  Two 
Harbors,  the  shipping  point,  is  twenty-six  miles  east  of 
Dulutb,  and  from  Tower,  the  principal  town  near  the  Vermil- 
ion Lake  mines,  it  is  sixty- seven  miles  to  the  docks.  Ely  is 
twenty- three  miles  northeast  of  Tower.  Leaving  the  lake  the 
railroad  first  crosses  with  heavy  grades  the  northwestern  flank 
of  the  Lake  Superior  synclinal,  chiefly  consisting  of  the  south- 
easterly dipping  trap  sheets  of  the  Keweenawan.  Underlying 
these  is  a  series  of  gabbros  and  augite  syenites — the  former  of 
which  contain  some  titan  if  erous  magnetites,  similar  to  those 
in  the  Adirondacks.  The  Mesabi  range  of  hills  succeeds  on 
the  north,  but  although  ore-bearing  further  west,  as  described 
under  the  next  example,  it  is  barren  at  this  point,  and  consists 
chiefly  of  black  slates,  referred  to  the  Animikie.  Sedimen- 
tary, gneissic  and  eruptive  rocks,  regarded  as  Laurentian  by 
the  Minnesota  geologists,  succeed,  and  give  place  finally  to  the 
metamorphic  rocks  of  the  Vermilion  range,  that  contain  the 
ore.  Still  further  north  are  the  Laurentian  rocks  again.  This 
whole  region  needs  further  and  very  detailed  mapping  to  accu- 
rately bring  out  its  geological  structure,  although  the  main 
points  mentioned  above  serve  to  outline  it.  The  immediate 
geological  relations  of  the  ores  have  been  elucidated,  however, 
by  the  recent  careful  work  of  H.  L.  Smyth  and  J.  R.  Fin  lay, 

consin,  III.,  pp.  100-167,  1880.  "Origin  of  the  Ferruginous  Schists  and 
Iron  Ores  of  the  Lake  Superior  Region,"  ^mer.  Jour.  Sci.,  iii.,  XXXII., 
263,  365;  see  also  under  Van  Hise.  C.  D.  Lawton,  "  Gogebic  Iron  Mines, " 
Engineering  and  Mining  Journal,  Jan  15,  1887,  p.  42.  C.  R.  Van  Hise, 
"  On  the  Origin  of  the  Mica  Schists  and  Black  Mica  Slates  of  the  Penokee- 
Gogebic  Iron-bearing  Series,"  Amer.  Jour.  Sci..,  iii.,  XXXI.,  453-459.  ''The 
Iron  Ores  of  the  Penokee-Gogebic  Series  in  Michigan  and  Wisconsin, 
Amer.  Jour.  Sci. ,  iii. ,  XXXVII. ,  32.  Irving  and  Van  Hise,  ' '  The  Penokee 
Iron-bearing  Series  of  Northern  Michigan  and  Wisconsin,"  Monograph 
XIX. ,  U.  S.  Geological  Survey,  1892.  Rec.  An  abstract  of  the  monograph 
will  be  found  in  the  Tenth  Annual  Rep.  Director  U.  S.  Geol.  Survey,  341. 
Rec.  C.  Whittlesey,  "The  Penokee  Mineral  Range,  Wisconsin,"  Proc. 
Bost.  Soc.  Nat.  Hist.,  IX.,  July,  1863.  C.  E.  Wright,  Geol.  Survey  of 
Wisconsin,  III.,  pp.  239-301. 


TEE  IRON  8EBIE8  CONTINUED. 


145 


Fig.  34. — Map  of  the  Minnesoto.  Iron  Ranges.     After  F.  W.  Denton,  I 
Amer.  Inst  Min.  Eng.,  XXVII.,  344. 


146  KEMP'S  CRE  DEPOSITS. 

to  which  the  subsequent  description  is  chiefly  due.  For  a 
thorough  reading  up  upon  the  district,  the  references  given 
below  will  suffice.^ 

The  Vermilion  Lake  mines  are  situated  on  the  top  of  an 
abrupt  hill  above  the  town  of  Soudan.  Some  ore  appears  in 
Lee  Hill,  a  mile  or  two  southeast,  near  Tower,  but  the  depos- 
its are  not  known  to  be  large.  The  mines  at  Soudan  extend 
for  about  a  mile  along  a  main  belt  in  a  direction  a  little  north 
of  east,  and  upon  a  more  or  less  parallel  minor  belt  that  lies  a 
short  distance  north.  This  alignment  is  due  to  the  intrusion 
of  a  great  mass  of  greenstone,  with  many  ramifying  dikes,  but 
all  on  this  general  line,  which  is  also  the  strike  of  the  jasper. 

On  the  northern  side  of  the  mines  the  surface  slopes  some- 
what sharply  to  Vermilion  Lake.  The  general  relations  are 
illustrated  by  the  accompanying  Fig.  35.  Smyth  and  Finlay 
have  shown  that  stratigraphically  there  are  two  series  of  sedi- 
mentary rocks,  both  of  which  have  been  penetrated  by  abun- 
dant intrusions  of  quartz  porphyry  and  diabase.  The  lower 
series  consists  of  slates  and  graj^wackes,  not  excessively  meta- 
morphosed. The  slates  are  at  times  carbonaceous  and  occa- 
sionally charged  with  pyrites.  Above  the  slates  lies  the  iron- 
bearing  formation,  consisting  of  quartz,  variously  intermingled 
with  hematite  or  magnetite,  or  quite  free  from  either.     The 

^  A.  H.  Chester,  Eleventh  Ann.  Rep.  Minn.  Oeol.  Survey,  155,  167.  T.  B. 
Comstock,  "  Vermilion  Lake  District  in  British  America,"  Trans.  Amer. 
Inst.  Min.  Eng.,  July,  1887.  F.  W  Denton,  "  Methods  of  Iron  Mining  in 
Northern  Minnesota,''  Idem,  XXVII.,  344.  R.  D.  Irving,  Seventh  Ann. 
Rep.  U.  S.  Geol.  Survey,  1885-86,  435.  H.  L.  Smyth  and  J.  R.  Finlay. 
"  The  Geological  Structure  of  the  Western  Part  of  the  Vermilion  Range, 
Minnesota,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXV.,  595-645,  1895.  Rec. 
C.  R.  Van  Hise,  Bull.  86,  U.  S.  Geol.  Survey.  Various  references  in  chap- 
ter ii.  Bailey  Willis,  Tenth  Census,  XV. ,  457.  Alexander  Winchell,  Fif- 
teenth Ann.  Rep.  Minn.  Geol.  Survey,  174.  Also  "Some  Results  of  Archean 
Studies,"  Bull.  Geol.  Soc.  Amer.,  I,  357.  H.  V.  Winchell,  "Diabasic  Schists, 
Containing  the  Jaspilyte  Beds  of  Northeastern  Minnesota, "  Amer.  Geol. ,  II. , 
18.  "The  Iron  Ranges  of  Minnesota,"  Proc.  Lake  Superior  Mining  Inst., 
III.,  1895.  Rec.  N.  H.  Winchell:  Many  references  to  the  region  by  N.  H. 
Winchell  are  to  be  found  in  the  reports  of  the  Minn.  Geol.  Survey.  They 
are  practically  summarized  in  the  next  reference.  N.  H.  and  H.  V. 
Winchell,  "  The  Iron  Ores  of  Minnesota,"  Bull.  6,  Geol.  Survey  of  Minn. 
Rec.  * '  On  a  Possible  Chemical  Origin  of  the  Iron  Ores  of  the  Kewatin 
in  Minnesota,"  ^wer.  Geol.,  TV.,  291,  389.  "The  Taconic  Iron  Ores  of 
Minnesota  and  Western  New  England,"  Amer.  Geol.,  VI.,  263. 


148  KEMP'S  ORE  DEPOSITS. 

varieties  occur  in  parallel  but  narrow  bands,  never  over  three 
or  four  inches  across,  and  doubtless  represent  the  original 
beds  of  the  sediment,  but  just  what  the  character  of  the  origi- 
nal sediment  was,  whether  the  cherty  carbonates  of  the  south 
shore  or  the  probable  glauconites  of  the  Mesabi  range  is  hope- 
lessly destroyed  b^^  metamorphism.  These  sediments  each 
form  three  belts,  as  shown  in  Fig.  35,  which  are  repeated 
because  of  sharply  compressed  and  pitching  folds.  After  the 
formation  of  the  sediments,  but  before  the  folding,  intrusions 
of  quartz  porphyry  and  diabase  took  place,  as  dikes  and  sheets, 
some  large,  others  of  excessive  thinness.  Subsequently  all 
suffered  severely  from  compression.  A  larger  series  of  folds 
was  developed  along  an  east  and  west  line,  and  a  smaller  series 
at  right  angles  to  this.  This  severe  compression  and  shearing 
changed  the  quartz  porphyries  in  large  part  to  conglomerate 
breccias,  and  to  sericite  schists,  while  the  diabases  passed  into 
chlorite  or  actinolite  schists  or  conglomerate  breccias.  The 
breccias  first  resulting  from  the  crushing  have  had  their  frag- 
ments so  rubbed  upon  one  another  that  they  are  stretched  and 
rounded  and  have  their  interstices  filled  with  sericite  schist  or 
chlorite  schist,  as  the  case  may  be.  The  brecciationtook  place 
on  the  anticlinal  crests,  but  in  the  synclinal  troughs  schists 
resulted.  These  foldings  also  formed  troughs  especiallj"  from 
the  corrugated  greenstone  dikes  and  from  the  intersections  of 
the  same,  and  when  the  iron- bearing  formation  stood  over  such 
a  trough,  it  passed  through  the  same  series  of  changes  that  have 
been  earlier  outlined  under  the  Marquette  range,  so  that  the 
iron  oxide  became  concentrated  along  the  sides  and  on  the  bot- 
toms, while  the  silica  was  removed.  The  accompanying  fig- 
ures exhibit  cross-sections  in  all  respects  like  those  on  the 
south  shore.  The  ores  are  all  hard,  dense,  specular,  and  are 
about  half  of  bessemer  and  half  oi  nou-bessemer  grade. 

2.02.26.  The  geological  relations  at  Ely  are  practically  the 
same,  but  the  ore  body  as  displayed  in  the  Chandler  and  Pioneer 
mines  is  larger  than  at  Vermilion  Lake.  It  rests,  however,  on 
a  greenstone  dike,  which  is  folded  into  a  syncline  with  a  minor 
roll  in  the  bottom  of  the  trough  which,  as  shown  in  Fig.  38, 
makps  it  a  double  one.  The  ores  are  soft  hematites  of  extraor- 
dinary richness  and  purity,  and  are  all  of  very  high  bessemer 
grade.     Indications  of   ore  are  strong  still  further  east,  and 


Fi«.   37. — Open  ciO  at  Minnesota  Iron  Company's  Mine,  Soudan,  near 
Tower,  in  south  view  looking  west.     Photograph  by  J.  F.  Kemp,  1894. 


Ph 


•<yf^<>*5'-''* 


t 


SI 


^^ 


150 


KEMP'S  ORE  DEPOSITS. 


developments  have  now  proved  important.  The  combined 
output  of  the  mines  at  Ely  and  Vermilion  Lake  is  from  800,000 
to  over  1,000,000  tons  annually,  about  equally  divided  between 
them.  The  total  shipments  up  to  the  close  of  1897  have  been 
10,498,716  tons. 

The  work  of  H.  L.  Smyth  and  Finlay  has  demonstrated  what 
many  observers  have  felt  from  more  cursor}^  examination — 
that  the  geological  relations  of  these  ores  are  essentially  the 
same  as  those  on  the  south  shore.  Different  explanations  have, 
however,  been  advanced,  and  great  uncertainty  has  surrounded 
the  geology,  on  account  of  the  excessively  metamorphosed  and 


Fig.  JjS. — Horizontal  and  vertical  cross-sections  of  the  Chandler  ore  body  at 
Minn.     After  Smyth  and  Finlay,  Trans  Amer.  Inst.  Min. 
Kng.,  XXV.,  595,  1895. 

obscure  igneous  rocks.  N.  H.  and  H.  V.  Winchell  have  argued 
that  the  ores  were  submarine  precipitates  from  volcanic  lapilli, 
furnished  by  submarine  eruptions.  From  the  lapilli  the  sea 
water  was  thought  to  have  extracted  the  iron  and  silica.  There 
seems,  however,  little  reason  to  question  the  results  of  Smyth 
and  Finlay. 

2.02.27.  Example  9e.  Mesabi  Range.  Of  much  more 
recent  development  than  the  other  districts  is  the  Mesabi 
range  of  Minnesota.  The  mines  began  to  make  important 
shipments  of  ore  in  1893.  The  indications  are  that  the  depos- 
its are  not  less  extensive  than  those  in  any  other  of  the  Lake 


THE  IRON  SERIES  CONTINUED. 


151 


Superior  localities,  and  that  they  are  even  larger  and  of  a  char- 
acter to  be  more  easily  mined.  The  present  developments  are 
situated  southwest  of  Vermilion  Lake,  and  nearer  Duluth  and 
Lake  Superior.  They  cover  a  stretch  of  about  30  miles,  from 
Biwabik  on  the  east,  through  McKinley,  Virginia,  Eveleth, 
Mountain  Iron  and  smaller  towns  to  Hibbing  on  the  west. 
Little  ore  is  known  beyond  Hibbing.  The  ore  bodies  are  all 
south  of  the  granite  ridge.  The  ore  lies  under  the  black  slates 
called  Animikie  in  the  section  given  in  Paragraph  2.02.2$,  and 
over  the  quartzite,  there  called  the  Pewabic;  but  they  are 
situated  twenty  miles  or  so  west  of  the  line  of  that  section.     The 


G    R    E 


Fig.  40. — General  cross-section  of  ore  body  at  Biwabik,  Mesabi  Range,  Minn. 
After  H.  V.  Winchell,  Twentieth  Ann.  Rep.  Minn.  State  Geologist. 

ore  bodies  are  all  south  of  the  granite  ridge  called  the  Giants' 
Range.  Upon  the  southern  slopes  of  this  range  lie  the  green 
schists  of  the  Keewatin,  which  are  unconformably  overlain  by 
the  Pewabic  quartzite.  On  this  rests  the  ore-bearing  rock, 
which  is  a  jaspery  or  cherty  siliceous  variety  called  taconyte 
by  H.  V.  Winchell.  Over  this,  in  order,  come  greenish  siliceous 
slates  and  cherts,  black  slates  (referred  to  the  Animikie),  and 
great  masses  of  gabbro.  On  the  flanks  of  the  Giants'  Range 
the  dip  is  steep,  but  it  flattens  out  nearly  to  horizontality  away 
from  the  granite.  All  the  formations  above  the  Keewatin  are 
called  Taconic  by  the  Winchells. 


152  KEMP'S  ORE  DEPOSITS. 

2.02.28.  The  ore  bodies  lie  on  the  southerly  slopes  of  low 
hills,  and  are  found  immediately  below  the  mantle  of  glacial 
drift,  which  varies  up  to  200  feet  in  thickness.  Ore  indications 
have  long  been  known  on  the  range,  and  various  reports  have 
been  made  in  former  years,  although  always  unfavorably.  The 
indications  then  available  showed  only  siliceous  limonites  of 
low  grade.  Deep  test  pits,  however,  which  penetrated  these 
caps  and  the  drift,  have  revealed  enormous  ore  bodies  and 
have  rewarded  persistent  prospecting.  The  ores  are  blue  and 
brown  and  of  soft,  earthy  texture,  with  occasional  hard  streaks. 
They  lie  from  10  to  as  much  as  180  feet  below  the  surface  a& 
now  mined,  and  where  the  stripping  is  sufficiently  thin  it  is 
removed  with  steam  shovels,  and  then  after  being  shaken  up 
with  black  powder  the  ore  is  excavated  in  the  same  way.  The 
ore  bodies  are  lenses,  which  at  times,  as  at  the  Mesaba  Mountain 
or  Oliver  mine  in  Virginia,  appear  to  form  a  basin.  In  the 
central  part  of  this  mine  a  drill  hole  is  stated  to  have  shown 
335  feet  of  ore,  but  the  general  run  is  less.  The  ore  bodies  have 
usually  a  southeasterly  trend,  and  are  longer  than  wide.  The 
blue  ores  are  richest  in  iron  and  purest  as  regards  phosphorus, 
and  they  are  the  ones  specially  desired.  Ores  for  foundry  iron 
also  occur  in  large  amount,  but  are  at  present  less  sought  for. 
The  rock  most  intimately  associated  with  them  all  is  the  chert, 
called  taconyte.  The  underlying  quartzite  is  occasionally 
shown  in  the  mines  as  well  as  the  overlying  slates,  but  the 
whole  region  is  so  completely  buried  in  drift  that  outcropping 
rock  is  a  rare  thing. 

The  ores  are  thought  by  H.  V.  Winchell  to  have  originated 
b}^  replacement  of  the  taconyte.  The  rock  contains  calcareous 
streaks  which  have  perhaps  aided  in  furnishing  the  carbonic 
acid,  which,  it  is  thought,  has  dissolved  the  silica  of  the  taconyte 
in  the  replacement  process.  Recently,  valuable  observations 
on  the  geology  of  the  ores  have  been  accumulated  by  J.  E. 
Spurr,  while  in  the  field  for  the  Minnesota  Geological  Survey, 
in  whose  Bulletin  X.  the  detailed  report  has  appeared.  A 
preliminary  paper  in  the  American  Geologist  for  May,  1894, 
gives  an  abstract  of  the  results.  As  in  the  Penokee-Gogebie 
and  Marquette  districts,  the  western  end  of  the  Mesaba  range  is 
least  disturbed  and  metamorphosed.  The  stratigraphy  is  the 
same  as  that  already  outlined  in  preceding  paragraphs,  but  the 


05 
GO 

si 

?= 

s 
1 


1 


THE  IRON  SEUIE8  CONTINUED.  153 

quartzite  is  simply  called  by  Spurr,  Animikie,  and  not  Pewa- 
bic.  The  iron-bearing  series  is  stated  to  be  from  500  to  1,000 
feet  thick,  with  an  average  of  800  feet.  The  unaltered  rock  is 
described  as  consisting  of  **cryptocrystalline,  chalcedonic  or 
finely  phenocrystalline  silica"  thickly  "strewn  with  rounded 
or  subangular  bodies  made  up  chiefly  of  a  green  mineral," 
regarded  as  glauconite,  the  hydrated  silicate  of  protoxide  of 
iron  and  potash.  Analyses  of  the  rock  corroborate  this  deter- 
mination, because  they  indicate  a  constant  but  small  percent- 
age of  potash.  Layers  of  the  rock,  rich  in  calcite  (probably 
magnesian)  also  occur.  Spurr  is  thus  led  to  regard  the  rock  as 
an  altered  greensand,  to  which  view  similar  conclusions  regard- 
ing the  much  more  recent  and  unmetamorphosed  ores  of  Texas 
and  Louisiana  (see  2.01.15)  give  support.  The  chemistry  of 
the  deposition  is  considered  by  Spurr  to  be  the  following: 
Atmospheric  waters,  with  dissolved  carbonic  acid,  and  some 
alkaline  salts  have  filtered  into  the  cracks  and  become  charged 
with  ferrous  carbonate,  where  the  conditions  prevented  oxidation. 
The  greater  solubility  of  the  ferrous  salt  led  to  its  solution 
before  the  alkali  attacked  the  silica. 

Later,  reaching  more  open  and  fissured  portions,  the  ferrous 
salt  was  oxidized  and  deposited,  while  the  silica  was  attacked 
and  removed  by  the  alkali.  In  time,  thus  the  iron  oxide  was 
concentrated  along  fissured  strips,  near  faults,  and  the  like, 
whereas  the  silica  was  removed.  It  is  recognized  as  well  that 
the  ferrous  salt  was  precipitated  as  carbonate,  amid  deoxidiz- 
ing conditions.  The  change  from  silicate  or  carbonate  to 
hydrous  oxide  of  iron  led  to  shrinkage  and  shattering,  and  the 
passage  from  hydrous  oxide  to  carbonate,  where  such  occurred, 
to  expansion  and  shattering.  It  follows  from  the  explanation 
that  the  regions  of  rich  ore  bodies  would  be  those  of  notable 
geological  disturbances,  so  that  faults  are  presumed  near  Vir- 
ginia, Biwabik  and  elsewhere.^ 

^  C.  E.  Bailey,  "Mining  Methods  on  the  Mesabi  Range,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XXVII.,  529.  F.  W.  Denton,  "Open-pit  Mining  with 
Special  Reference  to  the  Mesabi,"  Proc.  Lake  Superior  Mining  Inst.,  III., 
1896.  "Methods  of  Iron  Mining  in  Northern  Minnesota,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XXVII.,  344.  E.  P.  Jennings,  "The Mesabi  Range,"  Sci- 
ence, XXIII.,  73.  E.  J.  Longyear,  "Explorations  on  the  Mesabi  Range,' 
Trans.  Amer.  Inst.  Min.  Eng.,  XXVII.,   537.     J.  E.  Spurr,  "  The  Mesabi 


154  KEMP'S  OBE  DEPOSITS. 

2.02.29.  Hematites  apparently  much  like  those  of  Lake 
Superior  have  been  reported  from  the  Hartville  iron  district  in 
Laramie  County,  Wyoming.  The  ores,  according  to  W.  C. 
Knight,  constitute  irregular  zones  in  Carboniferous  rocks  and  are 
associated  in  many  cases  with  copper  deposits.  (See  2.04.28.) 
The  published  analyses  show  rich  ores  of  bessemer  grade. ^ 

2.02.30.  The  explorations  of  Mr.  A.  P.  Low,  of  the  Geologi- 
cal Survey  of  Canada,  have  shown  extensive  developments  of 
iron  carbonates,  and  magnetite  and  hematite,  associated  with 
jasper,  and  with  cherty  carbonate  of  lime,  along  the  east  side  of 
Hudson  Bay,  and  in  the  valleys  of  the  Koksoak  (called  also 
Ungava)  and  Hamilton  rivers.  Mr.  Low  describes  the  enclos- 
ing strata  as  Cambrian.  The  samples  brought  back  proved 
rather  low  in  iron  (30  to  54%  Fe),  but  the  geological  relations 
are  extraordinarily'  like  those  of  Lake  Superior.^ 

2.02.31.  Example  10.  James  River,  Virginia.  Specular 
hematite  in  narrow  beds  (lenses),  interstratified  with  quartzites 
and  slates  of  metamorphic  character  and  Archean  age.  They 
run  four  to  six  feet,  or  less,  in  thickness,  with  prevailingly 
vertical  dip,  but  they  also  pitch  diagonally  down  on  the  dip 
like  the  lenses  of  magnetite,  later  described.  They  furnish  a 
very  excellent  grade  of  ore.  The  ore  bodies  are  found  along 
both  sides  of  the  James  River,  a  few  miles  above  Lynchburg. 
Some  magnetite  also  occurs  in  the  region,  and  some  limonite. 
More  or  less  clay  accompanies  the  ore.^ 

Iron-bearing  Rocks, "  Bulletin  10,  Minn.  Geol.  Survey,  1894.  Rec.  '  *  The  Iron 
Ores  of  the  Mesabi  Range,"  Amer.  Geologist,  XIII.,  May,  1894,  335.  H.  V. 
Winchell,  Twentieth  Ann.  Rep.  Minn.  State  Geol.,  112,  1892.  "Iron  Ores 
of  Minnesota,"  Bull.  6,  Minn.  Geol.  Survey.  H.  V.  Winchell  and  J.  T. 
Jones,  "The  Biwabik  Mine,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXI.,  951. 
For  an  early  account  of  the  Mesabi  Range  see  New  York  Times,  December 
14,  1892. 

*  W.  C.  Knight,  Bulletin  U,  Wyoming  Experiment  Station,  Laramie, 
Wyo.,  pp.  135  and  176.  A  large  series  of  analyses  appears  in  the  prospec 
tus  of  the  Wyoming  Railway  and  Iron  Co.  E.  P.  Snow,  "  The  Hartville 
Iron  Ore  Deposits  in  Wyoming,"  Engineering  and  Mining  Journal,  Octo- 
ber 5,  1895,  p.  320. 

^  The  above  note  is  due  to  the  courtesy  of  Dr.  George  M.  Dawson,  Di 
rector  of  the  Geological  Survey  of  Canada,  who  kindly  gave  the  writer 
an  abstract  of  Mr.  Low's  report  in  advance  of  its  publication. 

'  E.  B.  Benton,  Tenth  Cenms,  Vol.  XL,  p.  363  (on  Virginia).  J.  L. 
Campbell,  Geology  and  Resources  of  the  James  River  Valley,  p.  49,  Nei^ 


THE  IRON  SERIES  CONTINUED.  155 

2.02.32.  Similar  lenses  of  specular  ore  and  magnetite  are 
found  in  central  North  Carolina,  in  schistose  rocks,  which 
have  been  referred  to  the  Huronian. 

As  stated  under  2.02.29,  lenses  of  specular  hematite  of  very 
excellent  quality  are  found  also  in  metamorphic  rocks,  north 
of  Fort  Laramie,  Wyoming,  which  may  prove  productive  in  time. 

2.02.33.  Example  11.  Pilot  Knob,  Missouri.  Two  beds  of 
hard  specular  hematite  separated  by  a  thin  seam  of  so-called 
slate  (possibly  volcanic  tuff),  and  interstratified  with  breccias 
and  sheets  of  porphyry.  Along  the  eastern  limit  of  the  Ozark 
uplift  of  Missouri  and  Arkansas  a  series  of  knobs  of  granite 
and  porphyritic  rocks  project  through  the  Cambrian  limestones 
and  sandstones.  They  are  older  than  the  limestones,  and 
clearly  were  not  intruded  through  them.  The  limestones  and 
sandstones  lie  up  against  the  porphyry  and  in  the  valleys 
between.  The  underlying  porphyry  has  been  found  in  the  val- 
ley near  Pilot  Knob,  after  penetrating  four  hundred  feet  of 
sedimentary  rocks.  The  porphyry  and  ores  have  often  been 
called  Huronian,  but  in  view  of  the  recent  reorganization  of  the 
Huronian  (see  Example  9),  this  is  not  done,  nor  ever  has  been, 
on  any  accurate  grounds.  Pilot  Knob  is  formed  by  one  of 
these  eruptive  knobs.  It  consists  of  sheets  of  porphyries  that 
are  capped  by  porphyry  breccia,  and  two  ore  beds,  and  the  in- 
tervening slaty  rock  which  may  be  a  tuff.  The  beds  strike  and 
dip  13°  S.  S.  W.  The  hill  is  over  600  feet  high.  The  lower 
bed  has  furnished  most  of  the  ore,  running  from  25  to  40  feet 
thick,  and  affording  a  dense  bluish,  specular  hematite  of  from 
50  to  60%  Fe,  siliceous  and  very  low  in  phosphorus.  The 
upper  bed  is  irregular  and  of  lower  grade,  and  runs  from  6 
to  10  feet  thick.  The  Pilot  Knob  mines  in  this  solid  ore  are 
DOW  substantially  exhausted. 

Recent  drill  holes  on  the  northerly  slope  and  below  the  out- 
cropping face  of  ore  have  shown  that  under  the  Cambrian 
strata  of  the  valley  there  is  a  great  bed  of  ore  boulders  or 
breccia  in  clay,  much  as  is  the  case  at  Iron  Mountain,  later 
described.     Analyses  of  these  latter  ores  were  not,  however, 

York,  1882.  H.  B.  C.  Nitze,  "On  North  Carolina,"  Bulletin  No.  1,  North 
Carolina  Geol.  Survey,  1893.  B.  Willis,  Te^ith  Census,  Vol.  XV.,  p.  301. 
The  Virginias,  a  monthly,  formerly  published  by  Jed.  Hotchkiss,  at  Staun- 
ton, contains  much  information  on  Virginia  in  general. 


TT 


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Ci- 


THE  IRON  SERIES  CONTINUED.  157 

sufficiently  encouraging  for  development  during  the  recent  low 
prices  for  iron.  Doubtless  the  bed  will  afford  important  re- 
serves. 

2.02.34.  Near  Pilot  Knob  are  two  other  hills  of  porphyry, 
Shepherd  Mountain  and  Cedar  Mountain,  whose  ores  are 
structurally  more  related  to  Example  11a.  The  first  contains 
three  veins,  the  Champion,  the  North,  and  the  South.  They 
are  long  and  narrow  (4  to  10  feet)  strike  north  60°  to  70°  east, 
and  dip  70°  north.  The  Champion  vein  contained  a  little 
streak  of  natural  lodestone,  but  the  ore  is  mostly  specular. 

The  North  vein  ^hows  a  good  breast  of  ore  five  feet  wide, 
but  too  full  of  pyrite  to  be  available.  Cedar  Mountain  has  a 
vein  of  specular  ore.  Neither  hill  has  been  an  important  pro- 
ducer. Minor  veins  have  been  found  on  neighboring  porphyry 
hills  (Buford,  Hogan,  and  Lewis  mountains),  some  of  which 
contain  much  manganese. 

2.02.35.  Example  11a.  Iron  Mountain,  Missouri.  Veins 
of  hard,  specular  hematite  irregularly  seaming  a  knob  of  por- 
phyry. Iron  Mountain  is  five  or  six  miles  north  of  Pilot  Knob, 
and  is  a  low  hill  with  a  westerly  spur  called  Little  Mountain. 
It  has  also  a  northerly  spur.  It  consists  of  feldspar  porphy- 
ries, more  or  less  altered.  These  are  seamed  with  one  large, 
and  on  the  west  somewhat  dome-shaped,  parent  mass  of  ore  and 
innumerable  minor  veins  that  radiate  into  the  surrounding 
rock.  Upon  the  flanks  of  the  porphyrj^  hill  rests  a  mantling 
succession  of  sedimentary  rocks,  that  dip  away  on  all  sides. 
The  lowest  member  is  a  conglomerate  of  ore  fragments,  weath- 
ered porphyry,  and  residual  clay  left  by  its  alteration.  It  is 
regarded  by  Pumpellyas  formed  by  pre-Silurian,  surface  disin- 
tegration and  not  by  shore  action,  inasmuch  as  sand  does  not 
fill  the  interstices,  while  white  clay  from  decomposed  porphyry 
does.  It  is,  however,  overlain  by  a  thin  bed  of  coarse,  friable 
sandstone,  which  marks  the  advance  of  the  sea,  and  whose 
formation  preceded  the  limestones.  This  conglomerate  was  in 
later  years  the  principal  source  of  the  ore,  but  the  mines  are 
now  considered  to  be  worked  out.  It  was  mined  underground, 
hoisted  and  washed  by  hydraulic  methods,  like  those  employed 
in  the  auriferous  gravels  of  California,  and  then  jigged.  The 
apatite  has  largely  weathered  out  of  it.  The  rock  of  the 
mountain  itself,  in  the  cuts  of  the  mines,  is  largely  kaolinized. 


158  KEMP'S  ORE  DEPOSITS. 

and  exhibits  everywhere  the  effects  of  extreme  alteration.  The 
smaller  veins  that  penetrate  the  porphyry  show  at  times  casts 
or  much  altered  cores  of  apatite  crystals. 

2.02.36.  The  porphyries  of  Pilot  Knob  and  Iron  Moun- 
tain, in  thin  section,  are  seen  to  belong  to  quartz  porphyries, 
feldspar  porphyries,  and  porphyrites.  Both  orthoclase  and 
plagioclase  are  present  in  them,  and  many  interesting  forms  of 
structure.  One  significant  fact  is  that  they  are  everywhere 
filled  with  dusty  particles  of  iron  oxide,  probably  magnetite. 
An  eruptive  origin  was  originally  assigned  to  these  ores  by  J. 
D.  Whitney  {Metallic  Wealth  of  the  United  States,  p.  479, 
1854),  just  as  to  the  Lake  Superior  hematites.  The  later  in- 
vestigations of  Adolph  Schmidt  for  the  Missouri  Survey  in 
1871  arrived  at  a  different  conclusion.  Dr.  Schmidt  considered 
them,  whether  occurring  in  an  apparent  bed,  as  at  Pilot  Knob, 
or  in  various  more  or  less  irregular  veins,  as  at  Iron  Mountain, 
to  have  been  formed  either  by  a  replacement  of  the  porphyries 
with  iron  oxide  deposited  from  solution,  or  by  a  filling  in  the 
same  way  of  fissures,  probably  formed  by  the  contraction  of  the 
porphyry  in  cooling.  In  the  valuable  report  on  iron  ores  by  F. 
L.  Nason  in  the  Missouri  Geological  Survey  a  sedimentary 
origin  is  advocated  for  the  Pilot  Knob  beds.  They  are  con- 
ceived to  have  been  deposited  in  a  body  of  water  in  a  hollow, 
between  formerly  existing  porphyry  hills,  which  rose  above. 
In  the  course  of  weathering,  the  hills  became  the  valleys,  and 
the  early  sedimentary  beds  the  hilltop.  It  is,  however,  some- 
what difficult  to  understand  how  the  more  or  less  incoherent 
sediments  withstood  degradation  better  than  the  hard,  firm, 
porphyry  hills.  Some  such  origin  as  sedimentation  or  replace- 
ment is,  however,  the  only  reasonable  one.  It  is  not  improba- 
ble that  the  Pilot  Knob  ores  originated  in  the  saturation  and 
more  or  less  complete  replacement  of  layers  of  tuffs  with  in- 
filtrating iron  oxide. 

An  extended  table  of  analyses  of  Iron  Mountain  ores  will 
be  found  in  Mineral  Resources  of  the  United  States,  1889-90, 
p.  47.' 

^  G.  C.  Broadhead,  "The  Geological  History  of  the  Ozark  Uplift, "^me?*. 
Geol. ,  III. ,  6.  J.  R.  Gage,  '  *  On  the  Occurrence  of  Iron  Ores  in  Missouri, " 
Trans.  St.  Louis  Acad.  Sci.,  1873,  Vol.  III.,  p.  181.  E.  Harrison,  "  Age  of 
the  Porphyry  Hills,  Ibid.,  Vol.   II.,  p.  504.     E.  Ha  worth,  "A  Contribu- 


Fig.  43. — View  of  ojjen  cut  at  Pilo^  Knob,  Mo.,  aJiowing  the  bedded  char- 
acter of  the  iron  ore.     From  v  photograi^h  by  J.  F.  Kemp,  1888. 


f 

O 


THE  IRON  SERIES  CONTINUED. 


159 


ANALYSES   OP   HEMATITES,    RED   AND   SPECULAR. 

(The  same  discrimination  must  be  employed  in  looking  over  these  anal- 
yses that  was  emphasized  under  limonite. ) 


Fe. 

P. 

S. 

SiO^. 

Al,03  H,0. 

Clinton,  N.  Y.  (fossil  ore) 

Wisconsin  (fossil  ore) 

44.10 
51.75 
44.40 
51.63 
■  56.40 

0.650 
1.392 
0.115 
0.345 

0.230 

12.63 

5.45 

2.77 

Pennsylvania  (Mifflin  ore) 

0.028 

Tennessee  (Meigs  County) 

0.340 
0.883 
0.085 
0.530 
0.067 
0.009 
0.040 
0.015 
0.139 
0.020 



16.80 

0.50 

■  \:  \  •  • 

Antwerp,  N.  Y 

46.32 
59.41 
68.40 
64.83 
60.47 
65.50 
59.15 
49.89 
61.81 
70.00 

Missouri  (Crawford  County) 

Marquette  dist.,  Mich,   (specular) 

6.  bio' 

2.07 
3.60 
3.38 
5.75 
13.27 

Menominee  district,  Michigan.  . . 

2.03 

Iron  Mountain,  Mo 

Pilot  Knob,  Mo 

2.19 

James  River  (Maud  vein) 

Elba    

0.170 

5.97 

3.47 

Pure  mineral 

These  analyses  are  mostly  taken  from  State  reports  and  from 
Mineral  Resources  of  the  United  States.  They  are  intended 
to  illustrate  he  general  run  of  compositions,  but  for  Birming- 
ham and  Marquette  are  high.     Analyses  vary  widely. 

tion  to  the  Archaean  Geology  of  Missouri,"  Amer.  Geol,  I.,  280-363;  "Age 
and  Origin  of  the  Crystalline  Rocks  of  Missouri,"  Bull.  5,  Mo.  Geol.  Sur- 
vey, 1891.  A.  V.  Leonhard,  "Notes  on  the  Mineralogy  of  Missouri," 
Trans.  St.  Louis  Acad.  Sci.,  Vol.  IV.,  p.  440.  F.  L.  Nason,  "Report  on 
the  Iron  Ores  of  Missouri,"  Mo.  Geol.  Survey,  II.  Rec.  R.  Pumpelly, 
"Geology  of  Pilot  Knob  and  Vicinity,"  ilfo.  Geol.  Survey,  1872,  p.  5;  see 
also  remarks  on  Iron  Mountain,  Bull.  Geol.  Soc.  Amer.,  Vol.  II.,  p.  220. 
Rec.  W.  B.  Potter,  "The  Iron  Ore  Regions  of  Missouri,"  Journal  U.  S. 
Asso.  Charcoal  Iron  Workers,  Vol.  VI.,  p.  23.  Rec.  F.  A.  Sampson,  "A 
Bibliography  of  the  Geology  of  Missouri,  '  Bull.  2,  Mo.  Geol.  Survey,  1890. 
(This  is  a  valuable  book  of  reference. )  F.  Shepherd,  Ann.  Rep.  Mo.  Geol. 
Survey,  1853-54.  Hist.  A.  Schmidt,  "Iron  Ores  of  Missouri,"  ilfo.  Geol. 
Survey,  1872,  p.  45,  and  especially  p.  94.  Rec.  J.  D.  Whitney,  Metallic 
Wealth  of  the  U.  S.,  p,  479.     Of  more  recent  issues  are  the  following: 

E.  Ha  worth,  "The  Crystalline  Rocks  of  Missouri,"  Eighth  Ann.  Rep.  Mo. 
Geol.  Survey,  1894,  p.  81.  C.  R.  Keyes,  "Geographic  Relations  of  the 
Granites  and  Porphyries  in  the  Eastern  Part  of  the  Ozarks, "  J5«*/Z.  Geol. 
Soc.  Amer.,  VII.,  363,  1896.  "Report  on  the  Mine  la  Motte  Sheet,"  Geol. 
Survey  of  Mo.,  IX.,   Sheet  Report  4.     Arthur  Winslow,  E.  Haworth  and 

F.  L.  Nason,  "Report  on  the  Iron  Mountain  Sheet,"  Idem,  Sheet  Report 
3.  Rec.  This  last  is  the  best  work  of  reference  as  regards  the  mines. 
Further  details  will  be  found  in  Winslow's  Bulletin  132  of  the  U.  S.  Geol. 
Survey,  on  "The  Disseminated  Lead  Ores  of  Southeastern  Missouri." 


CHAPTER  III. 

MAGNETITE   AND  PYRITE. 

2.03.01.  Example  12.  Magnetite  Beds.  Beds  of  magne- 
tite, often  of  lenticular  shape,  interfoliated  with  Archean 
gneisses  and  crystalline  limestones.  They  are  extensively 
developed  in  the  Adirondacks,  in  the  New  York  and  New  Jer- 
sey Highlands,  and  in  western  North  Carolina.  The  presence 
of  magnetite  in  Michigan  (Example  9a),  in  Minnesota  (Exam- 
ple 6b),  on  Shepherd  Mountain  in  Missouri  (Example  11),  and 
in  Virginia  (Example  12)  has  already  been  referred  to.  Other 
magnetite  bodies  are  known  in  Colorado,  Utah,  California  and 
Wyoming,  and  will  be  mentioned  subsequently.  Titanium  is 
often  present,  but  the  titaniferous  ores  are  made  a  special  exam- 
ple. The  same  is  true  of  pyrite  and  pyrrhotite.  Apatite  is 
always  found,  although  it  may  be  in  very  small  quantity. 
Chlorite,  hornblende,  augite,  epidote,  quartz,  feldspar,  and  a 
little  calcite  are  the  common  associated  minerals.  In  New 
Jersey  the  beds  occur  in  several  parallel  ranges  or  belts. 

2.03.02.  Example  12a.  The  Adirondacks.  Deposits  of 
magnetite  are  extensively  developed  in  the  crystalline  area  of 
the  Adirondacks,  and  they  show  some  interesting  relationships 
between  the  character  of  the  ore  and  the  nature  of  the  country 
rock.  The  titaniferous  varieties  to  be  later  described  favor  the 
interior,  mountainous  core,  but  the  nontitaniferous  are  especially 
found  on  the  flanks  and  in  the  foothills.  The  region  is  in  large 
part  an  eruptive  area  of  plutonic  rocks  representing  various 
members  of  the  great  gabbro  family  whose  chief  minerals  are 
labradorite  and  some  form  of  pyroxene.  There  are  members 
which  are  little  else  than  labradorite  and  which  are  called 
anorthosites ;  there  are  others  containing  labradorite  and  hyper- 
sthene,  the  norites;  still  others  are  dark  and  basic,  and  consist 


MAGNETITE  AND  P TRITE.  161 

of  little  else  than  labradorite,  augite,  hypersthene,  ilmenite 
and  garnets,  the  last-named  having  been  formed  by  metamor- 
phism/  Augite  syenites  of  massive  character  have  recently 
been  recognized  by  H.  Po  Gushing,  and  the  discovery  has 
thrown  much  light  on  many  rocks  only  known  before  as 
gneisses.  All  these  eruptives  have  suffered  greatly  from  dyna- 
mic metamorphism,  and  are  now  as  a  rule  decidedly  gneissoid 
in  structure.  In  addition  to  the  eruptives  there  are  white,  crys- 
talline, graphitic  marbles,  usually  charged  with  pyroxenes; 
black,  hornblendic  schists;  quartzites;  and  quartzose  gneisses 
that  represent  a  series  of  sedimentary  rocks  of  Algonkian 
age,  but  that  are  now  much  broken  by  the  eruptives  above 
mentioned.  The  Algonkian  sediments  are  most  satisfactorily 
exhibited  on  the  western  side  of  the  mountains. 

^  The  general  geology  of  the  Adirondacks  is  described  by  E.  Emmons  in 
his  "Report  on  the  Second  District  of  New  York,"  N.  Y.  Natural  History 
Survey,  1842.  The  later  papers  of  importance  are  the  following,  and  a 
general  review  of  work  that  had  been  done  up  to  1892  is  given  by  J.  F. 
Kemp,  "  A  Review  of  Work  Hitherto  Done  on  the  Geology  of  the  Adiron- 
dacks," Trans.  N.  Y.  Acad,  of  Sciences,  XII.,  19,  1892.  H.  P.  Gushing,  "Re- 
port on  the  Geology  of  Clinton  Co.,"  13th  Ann.  Rep.  State  Geologist,  1893, 
473;  16th  Idem,  499.  ' '  Report  on  the  Boundary  Between  the  Potsdam  and 
Pre-Cambrian  Rocks  North  of  the  Adirondacks,"  16th  Annual  Report 
State  Geologist,  1896.  An  additional  report  on  'Franklin  Co.  is  in  press 
(1899).  "Augite- syenite  Gneiss  near  Loon  Lake,  N.  Y.,"  Bull.  Geol.  Soc. 
Amer.,  X.,  177-192.  J.  F.  Kemp,  "  Gabbros  on  the  Western  Shore  of  Lake 
Champlain,"  Jdem,  V.,  213,  1894.  "Crystalline  Limestones,  Ophicalcites 
and  Associated  Schists  of  the  Eastern  Adirondacks, "  Idem,  VI. ,  241.  ' '  Pre- 
liminary Report  on  the  Geology  of  Essex  Co.,"  Rep.  N.  Y.  State  Geologist 
for  1893,  79,  1894;  continued  in  the  ISth  Ann.  Rep.,  Idem,  1895,  575.  A 
report  on  Warren  Co.  is  in  press.  ' '  The  Geology  of  Moriah  and  Westport 
Townships,  Essex  Co.,"  Bull.  N.  Y.  State  Museurn,  III.,  325,  1895.  "The 
Geology  of  the  Magnetites  near  Port  Henry,  N.  Y.,  Trans.  Amer.  Inst. 
Min.  Eng. ,  XXVII. ,  146,  1897.  ' '  The  Geology  of  the  Lake  Placid  Region, " 
Bull.  N.  Y.  State  Museum,  V.,  51,  1898.  C.  H.  Smyth,  Jr.,  "A Geological 
Reconnoissance  in  the  Vicinity  of  Gouverneur,  N.  Y. ,  Trans.  N.  Y.  Acad. 
Sci.,  XII.,  203,  1893.  "Petrography  of  the  Gneisses  of  the  Town  of  Gouv- 
erneur, N.  Y.,"  Idem,  XII.,  203,  1893.  "Report  on  the  Geology  of  Four 
Townships  in  St.  Lawrence  and  Jefferson  Counties,"  13th  Ann.  Rep. 
N.  Y.  State  Geologist,  491.  "Crystalline  Limestones  and  Associated  Rocks 
of  the  Northwestern  Adirondack  Region,"  Bull.  Geol.  Soc.  Amer.,  VI.,  263, 
189d.  ' '  Report  on  the  Crystalline  Rocks  of  St.  Lawrence  Co. , "  15th  Ann. 
Rep.  N.  Y.  State  Geologist,  1895,  477.  Additional  reports  on  the  western 
Adirondacks  are  in  press. 


162  KEMP'S  ORE  DEPOSITS. 

2.03.03.  The  magnetites  are  found  in  the  fortn  of  lenticular 
masses  that  correspond  perfectly  to  the  foliation  of  the  gneisses. 
They  may  extend  long  distances  on  the  strike,  as  at  Lyon 
Mountain,  where  the  Chateaugay  ore  is  said  to  be  traceable 
four  or  five  miles,  but  it  is  lean  over  most  of  the  distance.  Beits 
more  or  less  continuous  for  a  mile  are  opened  up  in  several 
places.  The  ore  may  be  in  gneiss  that  is  practically  quartz 
and  microperthite  as  at  Hammond ville;  or  in  pyroxenic  gneisses 
as  at  Lj^on  Mountain ;  or  on  the  contact  of  gneiss  like  that 
which  forms  the  wall-rock  at  Hammondville  just  mentioned, 
and  dark,  basic,  hornblendic  gneiss,  derived  from  intruded 
gabbro;  or  on  the  contact  of  gabbro  like  the  last  and  gneisses 
which  are  involved  with  crystalline  limestones,  as  at  the  Chee- 
ver  mine;  or  finally,  in  the  crystalline  limestones  near  gabbro 
intrusions,  as  at  the  Weston  niines,  Keene  Center.     The  ores  at 


SOOFeet 

Fig.  47. — Gross-section  of  the  Chee'cer  iron  mine,  near  Port  Henry,  N.  Y., 

showing  the  occurrence  of  the  ore  in  pyroxene  gneiss,  just  over  gabhro. 

Lake  Champlain  'terminates  the  section  at  the  right.     After 

J.  F.  Kemp,  Bull.  N.  T.  State  Museum,  Vol.  III.,  p.  346. 

Mineville  have  been  regarded  as  contact  deposits  hy  J.  F. 
Kemp,  and  as  having  been  developed  by  the  neighboring  gab- 
bro. As  will  appear  from  the  accompanying  map  and  sections, 
Figs.  48  and  49,  there  are  two  groups  of  mines.  One  on  Bar- 
ton Hill  is  based  on  a  long  series  of  pods  or  lenses  that  occur 
between  an  underlying  gabbro  and  gabbro-gneiss,  and  an  over- 
lying gneiss,  called  the  Orchard.  The  Orchard  gneiss  con- 
sists almost  entirely  of  quartz  and  oligoclase.  Above  it  is  the 
Barton  gneiss,  containing  some  quartz  with  abundant  micro- 
perthite, plagioclase,  orthoclase,  brown  hornblende,  augite  and 
hypersthene.  The  lower  group  embracing  the  Miller  pit,  Old 
Bed  and  *'2.1,'*  have  the  *'21''  gneiss,  an  aggregate  of  quartz 
and  microperthite,  exposed  on  the  surface.  Diamond  drill  cores 
have,  however,  revealed  the  gabbro-gneiss  beneath  the  ore  in 
depth.     The  map  brings  out  the  parallel  pod-like  shape  of  the 


Fig.  46.  —  View  of  open  cut  and  underground  work  in  Mine  21,  Mineville, 
near  Port  Henry,  N.  Y.     Photographed  by  J.  F.  Kemp,  1892. 


MAGNETITE  AND  PYRITE. 


163 


Fig.  48. — Heological  map  of  the  iron  mines  at  Mineville,  near  Port  Henry, 

N.  Y.    For  details  of  formations  see  text.     After  J.  F.  Kemp,  Trans. 

Amer.  Inst.  Min.  hJng.,  XXVIL,  146. 


164 


KEMP'S  ORE  DEPOSITS. 


ores.  In  one  instance,  the  New  Bed  mines,  the  workings  have 
followed  a  pod  over  2,000  ft.  The  magnetites  have  not  yet 
been  described  in  the  same  detail  at  other  localities,  but  data 
are  at  hand  which  give  ground  for  similar  inferences  regarding 
several  additional  ones.  Gabbros  are  usually  in  the  vicinity 
of  the  ore  even  when  it  does  not  occur  on  the  contact.  Never- 
theless some  mines  give  no  immediate  evidence  of  the  influence 
of  any  rock  except  that  of  the  walls,  as  for  instance  the  Palmer 
Hill  workings  near  Ausable  Forks;  and  the  ore  appears  to  be 
a  great,   basic  segregation,  drawn  out  into  a  band,   parallel 


Fig.  49. — Cross-section  of  ore-bodies  at  Mineville,  near  Port  Henry,  N.  Y.,  to 

accompany  rnap,  Fig.  48.     After  J.  F.  Kemp,  Trans.  Amer. 

Inst.  Min.  Eng.,  XXVII,  146. 

with  the  foliation.  At  Palmer  Hill  the  walls  are  a  siliceous 
gneiss,  consisting  of  quartz,  microperthite,  microcline  and 
augite. 

The  ores  follow  all  the  foldings  and  flowing  curves  that  are 
exhibited  in  the  foliation  of  the  gneisses,  and  because  of  this 
they  exhibit  manj-  peculiar  shapes.  They  swell  and  pinch,  roll 
and  fold  and  feather  out.  Still,  at  Mineville  they  show  a 
marked  parallelism  in  the  long  axes  of  the  pods  or  lenses,  and 
while  these  tongue  out  into  the  walls,  they  do  so  with  a  gen- 
eral parallel  alignment.  Faults  are  common  and  in  instances 
have  sharply  cut  off  the  ore.  Dark,  brecciated  strips  may  mark 


I 


MAGNETITE  AND  PYBITE.  165 

the  fault  line  and  may  resemble  trap  dikes,  as  in  No.  7  slope  at 
Hammond ville.  Small  gulches  are  frequently  over  the  places 
where  the  ore  is  lost,  and  serve  to  mark  the  fault  line.  Trap 
dikes  are  frequent  in  the  mines,  and  hardly  a  solitary  one  fails 
to  show  them.     They  may  fault  the  ore  for  a  few  feet.^ 

2.03. 04.  In  their  metallurgical  relations  the  ores  may  be  clas- 
sified, following  the  example  of  B.  W.  Putnam  in  his  report 
for  the  Tenth  Census,  into  (1)  those  high  in  phosphorus,  but 
low  in  sulphur  (Mine  21,  Mineville);  (2)  Bessemer  ores,  low  in 
both  phosphorus  and  sulphur  (Barton  Hill  mines,  Hammond- 
ville  mines);   (3)  pyritous  ores  (Buck  Mountain,  Ticonderoga). 

*  The  following  papers  relate  especially  to  the  ores  as  distinguished  from 
the  geology:  L.  C.  Beck,  Mineralogy  of  New  York,  Part  I.,  1-38,  1842. 
J.  Birkinbine,  " Crystalline  Magnetite  in  the  Port  Henry  (N.  Y.)  Mines," 
Trans.  Amer.  Inst.  Min.  Eng.,  XVIII.,  747,  1890.  Rec.  "Note  on  the 
Magnetic  Separation  of  Iron  Ore  at  the  Sanford  Ore- bed,  Moriah,  Essex 
Co.,  N.  Y.,  1852,  Idem,  XXI.,  378,  1892;  see  also  p.  157.  H.  Credner, 
Zeitsch.  d.  d.  g.  Gesell,  1869,  XXI.,  p.  516;  B.  und  H.  Zeit,  1871,  369. 
J.  D.  Dana  "On  the  Theories  of  Origin,"  Amer.  Jour.  Sci.,  iii.,  XXII.,  152, 
402.  E.  Emmons,  Geology  of  New  York,  Second  District,  pp.  87,  98,  231, 
255,  291,  309,  350.  Hist.  C.  E.  Hall,  "Laurentian  Magnetite  Ore  Depos- 
its of  Northern  New  York,"  3M  Ann.  Rep.  State  Museum,  1884,  p.  133. 
Rec.  Hanns  Hoefer,  * '  Die  Kohlen-  und  Eisenerzlagerstatten  Nord  Amer- 
ikas,"  175,  1878.  J.  F.  Kemp,  "Notes  on  the  Minerals  Occurring  near 
Port  Henry,  N.  Y.,"  Amer.  Jour.  Sci.,  iii.,  XI.,  62,  and  Zeitsch.  f.  Kryst., 
XIX.,  183.  "The  Geology  of  the  Magnetites  near  Port  Henry,  N.  Y.," 
Trans.  Amer.  Inst.  Min.  Eng.,  XXVI.,  146,  1897.  G.  W.  Maynard,  "The 
Iron  Ores  of  Lake  Champlain,"  Brit.  Iron  and  Steel  Inst.,  Vol.  I.,  1874. 
F.  L.  Nason,  "Notes  on  Some  Iron-bearing  Rocks  of  the  Adirondack 
Mountains,"  Amer.  Geologist,  XII.,  25,  1893.  B.  T.  Putnam  "Notes  on  the 
Iron  Mines  of  New  York, "  Tenth  Census,  XV. ,  89,  1885.  Rec.  B.  Silliman, 
"Remarks  on  the  Magnetites  of  Clifton,  St.  Lawrence  County,  N.  Y.," 
Trans.  Amer.  Inst.  Min.  Eng.,  I.,  364.  J.  C.  Smock,  "Iron  Mines  of  New 
York,"  Bull.  VII. ,  N.  Y.  State  Museum.  Rec.  J.  Stewart,  "Laurentian 
Low  Grade  Phosphate  Ores,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXI.,  176, 
1892.  Wedding.  Zeitschr.  f  B.,  H.,  und  S.  im.  p.  St.,  XXIV.,  330,  1876. 
See  also  the  general  works  on  Iron  Ores  cited  at  begimiing  of  Part  II.  On 
Canadian  magnetites  the  following  papers  may  be  mentioned:  F.  P 
Dewey,  "Some  Canadian  Iron  Ores,"  Trans.  Amer.  Inst.  Min.  Eng.,  XII. 
192.  B.  J.  Harrington,  "On  the  Iron  Ores  of  Canada,"  Can.  Geol.  Survey 
1873^74.  T.  S.  Hunt,  Can.  Geol.  Survey,  1866-69,  pp.  261,  262.  T.  D.  Led 
yard,  "Some  Ontario  Magnetites."  Traris.  Amer.  Inst.  Min.  Eng.,  XIX. 
28,  and  July,  1891.  W.  H.  Merritt,  "Occurrence  of  Magnetite  Ore  De 
posits  in  Victoria  County,  Ontario,"  Froc.  Amer.  Asso.  Adv.  Sci.,  XXXI. 
413.  1882. 


166 


KEMP'S  ORE  DEPOSITS. 


On  the  western  side  of  the  mountains  some  extensive  mining 
has  also  been  done.  The  Benson  mines  at  Little  Eiver  are 
based  upon  a  broad,  mineralized  zone  whose  ore  is  inclined  to 
be  lean,  and  to  be  a  subject  for  magnetic  concentration.  There 
are  numerous  deposits  of  magnetite  in  Canada,  to  the  north 
of  Lake  Ontario,  whose  geological  relations  are  similar  to  those 
above  described. 

2.03.05.  Example  126.  New  York  aud  New  Jersey  High- 
lands, and  the  South  Mountain  of  Pennsylvania,  Lenticular  or 
pod-like  masses  of  magnetite  in  Archean  gneiss  and  crystalline 


Fig.  oO.  Fig.  51. 

Figs.  50  and  51 . — Model  of  the  TiUy  Foster  ore  body.     50.  Side  mew,  show- 
ing faulted  shoulder.     After  F.  8.  Ruttmann,  Trans.  Amer.  Inst. 
Min.  Eng.,  XV.,  79.     51.  View  of  bottom  of  same.  Photo- 
graphed by  J.  F.  Kemp  from  the  model  now  at  the 
School  of  Mines,  Columbia  College. 

limestone.  From  Putnam  County,  New  York,  a  ridge  of 
Archean  rocks  runs  southwest  across  the  Hudson  River,  trav- 
ersing Orange  County,  New  York,  and  northern  New  Jersey, 
and  running  out  in  Pennsylvania.  Lenses  of  magnetite  occur 
throughout  its  entire  extent.  They  are  not  as  large  as  some 
in  the  Adirondacks,  but  they  are  more  regularly  distributed. 
East  of  the  Hudson,  in  Putnam  County,  the  Tilly  Foster 
mine    is     the    most    important,    and    the     descriptions     and 


MA  GNETITE  A  ND  P  YRl  TE.  167 

figures  of  it  are  the  best  illustrations  of  the  shape  of  lenses 
published.  West  of  the  Hudson,  in  Oranpje  Countj',  the 
Forest  of  Dean  mine  affords  considerable  ore  yearly.  It  is 
cut  by  an  interesting  trap  dike.  As  the  results  of  study 
of  the  Archean  of  this  region,  N.  L.  Britton  has  divided 
it  into  a  Lower  Massive  group,  a  Middle  Iron  Bearing, 
and  an  Upper  Schistose.  {Oeol.  of  N.  J.,  1886,  p.  77.) 
F.  L.  Nason  has  also  sought  to  classify  it  on  the  basis  of  rock 
types,  of  which  he  naakes  four,  named,  from  their  typical  occur- 
rences. Mount  Hope  type,  Oxford  type,  Franklin  type,  and 
Montville  type.  They  are  arranged  in  their  order  of  probable 
age.  They  correspond  in  some  respects  to  Britton's  grouping, 
but  differ  materially  in  others.  {Geol.  of  N.  J.,  1889,  p.  30.) 
Four  courses,  or  mine-belts,  have  been  recognized  in  New  Jer- 
sey— the  Ramapo,  the  Passaic,  the  Musconetcong,  and  the 
Pequest — in  order  from  east  to  west.  The  lenses  strike  north- 
east with  the  gneisses,  and  usually  have,  like  them,  high  dips. 
In  addition  they  have  also  a  so-called  "pitch"  along  the  strike, 
so  that  they  run  diagonally  down  the  dip.  They  have  been 
observed  to  pitch  northeast  with  an  easterly  dip  and  southwest 
with  a  westerly.  Either  by  the  overlapping  of  lenses  or  by  an 
approximation  to  an  elongated  bed,  they  sometimes,  as  at 
Hibernia,  extend  a  mile  or  more  in  unbroken  series.  Again, 
they  may  be  almost  circular  in  cross  section  (Hurd  mine).  At 
Franklin  Furnace  one  is  found  in  crystalline  limestone.^ 

'  E.  S.  Breidenbaugh,  "On  the  Minerals  Found  at  the  Tilly  Foster  Mine, 
New  York,"  Amer.  Jour  Sci.,  iii.,  VI.,  207.  J.  F.  Kemp,  "  Diorite  Dike  at 
the  Forest  of  Dean  Mine,"  Idem,  iii.,  XXXV.,  331.  F.  H.  McDowell, 
"The  Reopening  of  the  Tilly  Foster  Mine,"  Trans.  Amer.  Inst  Min. 
Eng.,  XVII.,  758;  Engineering  and  Mining  Journal,  Sept.  7,  1889, 
206.  F.  S.'  Ruttman,  "  Notes  on  the  Geology  of  the  Tilly  Foster  Ore 
Body,  Putnam  County,  New  York,"  Trans.  Ainer.  Inst.  Min.  Eng.,  XV., 
79.  Rec.  J.  C.  Smock,  Bull.  VIL,  N.  Y.  State  Museum.  Rec.  A.  F.  Wendt, 
'The Iron  Mines  of  Putnam  County,"  Trans.  Amer.  Inst.  Min.  Eng., 
XIII.,  478.  "Iron  Mines  of  New  Jersey,"  School  of  Mines  Quarterly,  iv., 
III.  N.  L.  Britton,  Ann.  Rep.  N.  J.  Sm^ey,  1886,  p.  77.  Rec.  G.  H. 
Cook  and  J.  C.  Smock,  Geol.  of  N.  J.,  1868.  Rec.  (See  also  subsequent 
annual  reports,  especially  1873,  p.  12.)  F.  L.  Nason,  Ann.  Rep.  N.  J. 
Survey,  1889.  Rec.  J.  W.  PuUmann,  "  The  Production  of  the  Hibernia 
Mme,  New  Jersey,"  Trans.  Amer.  Inst.  Min.  Eng.,  XIV.,  904.  J.  C. 
Smock,  "The  Magnetite  Iron  Ores  of  New  Jersey,"  Idem,  II.,  314;  "A 
Review  of  the  Iron  Mining  Industry  of  New  Jersey,"  Idein,  June,  1891. 
Rec. 


168 


KEMP'S  ORE  DEPOSITS. 


J.  E.  Wolff  has  contributed  a  very  important  and  suggestive 
paper  upon  the  large  bed  of  magnetite  at  Hibernia.  The  ore 
extends  for  about  one  mile  as  developed,  and  forms  a  persist- 
ent band  in  a  series  of  gneisses  which  under  the  microscope  are 
found  to  contain  quartz,  orthoclase,  plagioclase,  microcline, 
microperthite,  brown  or  green  hornblende,  a  deep  green  or  color- 


Fig.  52. — Sketch  map  illustrating  the  geological  structure  of  the  Hibernia  mag- 
netite bed,  Hibernia,  N.  J.     The  ore  outcrops  for  one  mile.     After  J.  E. 
Wolff,  Annual  Report  of  the  State  Geologist  of  New  Jersey  for  1893. 

less  augite,  sometimes  diallage,  biotite,  sometimes  hypersthene, 
and  as  accessories,  apatite,  magnetite,  and  zircon.  The  dark 
silicates  may  form  int;ermittent  bands  by  their  greater  abund 
ance,  but  are  of  no  stratigraphic  value.  All  the  large  minerals 
are  in  elongated  spindles,  whose  long  axes  correspond  to  the 
pitch  of  the  gneiss.     They  are  thought  by  Wolff  t;o  have  as- 


MAGNETITE  AND  P TRITE.  169 

sumed  this  shape  in  crystallizing,  during  metamorphism.  About 
a  half  mile  from  the  ore  and  parallel  with  it  is  a  band  of 
biotite-garnet-graphite  gneiss  that  is  persistent,  and  that  is 
folded  as  shown  in  Fig.  52.  This  latter  rock"  is  supposed  to 
be  a  metamorphosed  limestone,  and  the  whole  series  is  regarded 
as  metamorphosed  sediments  by  Wolff. ^  F.  L.  Nason  has 
worked  out  the  structural  geology  of  the  Ringwood  mines,  and 
has  found  that  they  are  quite  well  interpreted  as  lying  along  a 
pitching  series  of  folded  gneisses.^ 

2.03.06.  South  Mountain,  Pa.  Small  lenses  of  magnetite 
occur  in  Berks,  Bucks,  and  Lehigh  Counties  of  southeastern 
Pennsylvania,  in  the  metamorphic  rocks  of  the  South  Moun- 
tain belt.  They  are  very  like  those  to  the  north  in  New  Jer- 
sey, but  are  lower  in  both  iron  and  phosphorus.  Their  product 
has  reached  100,000  tons  5'early.  The  Cornwall  magnetite  is 
described  under  Example  13,  for  its  geological  structure  is 
entirely  different  from  the  lenses.^ 

2.03.07.  Example  12c.  Western  North  Carolina  and  Vir- 
ginia. Beds  of  magnetite,  of  the  characters  already  described, 
in  Archean  gneisses  and  schists.  The  ore  body  at  Cranberry, 
N.  C,  is  the  largest  and  best  known.  It  occurs  in  Mitchell 
County,  and  has  lately  been  connected  by  rail  with  the  lines  in 
east  Tennessee.  According  to  Kerr,  the  principal  outcrop  is 
1,500  feet  long  and  200  to  800  feet  broad ;  but,  of  course,  this  is 
not  all  ore.  The  mines  can  afford  very  large  quantities  of  excel- 
lent Bessemer  grade.  Pyroxene  and  epidote  are  associated  with 
the  ore.  Kerr  has  referred  the  magnetite  to  the  Upper  Lauren- 
tian.  In  the  southern  central  portions  of  North  Carolina  other 
magnetites  occur  in  the  mica  and  talcose  schists,  which  have 
been  referred  to  the  Huronian.  (See  H.  B.  C.  Nitze,  Bull. 
I.,  N.  C.  Geol.  Survey,  toT  detailed  report)  (Example  10.) 
Magnetite  has  also  been    lately  reported  from  Franklin  and 


'  J.  E.  Wolff,  "Geological  Structure  in  the  Vicinity  of  Hibernia,  N.  J., 
and  its  Relation  to  the  Ore  Deposits,"  N.  J.  Geol.  Survey,  1893,  859. 

^  F.  L.  Nason,  "  The  Geological  Structure  of  the  Ringwood  Iron  Mines, 
N.  J.,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXIV.,  505,  1894. 

3  E.  V.  d'Invilliers,  Rep.  D3,  Penn.  Survey,  Vol.  II.  (South  Mountain  Belt 
of  Berks  County).  Rec.  F.  Frime,  Rep.  DS,  Vol  I.,  Penn.  Survey  (Lehigh 
County).     B.  T.  Putnam,   Tenth  Census,  Vol.  XV.,  p.  179. 


170  KEMP'S  ORE  DEPOSITS. 

Heory  Counties,  Virginia,  and  Stokes  County,  North  Carolina. 
Some  doubt,  however,  is  cast  on  its  amount  and  quality/ 

2.03.08.  Example  Vld.  Colorado  Magnetites.  Beds  of 
magnetite  of  a  lenticular  character  in  rocks  described  as  sye- 
nite (Chaffee  County)  and  diorite  (Fremont  County).  With 
these  a  number  of  others  are  mentioned  which  vary  from  the 
example,  but  of  which  more  information  is  needed  before  they 
can  be  well  classified.  The  last  are  mere  prospects.  The  mines 
in  Chaffee  County  have  been  the  only  actual  producers.  There 
are  three  principal  claims — the  Calumet,  Hecla  and  Smithfield. 
They  extend  continuously  over  4,000  feet.  The  wall  rock  is 
called  syenite.  Chauvenet  describes  them  as  having  resulted 
from  the  oxidation  of  pyrites,  and  as  being  in  rocks  of  Silurian 
age.  They  average  57%  Fe,  with  only  0.009  P,  but  are 
comparatively  high  in  S,  reaching  0.1  to  2.0%.  These 
mines  and  those  at  the  Hot  Springs,  mentioned  under  Ex- 
ample 2,  have  furnished  the  Pueblo  furnaces  with  most  of 
their  stock.  The  deposit  in  Fremont  County  is  at  Iron  Moun- 
tain, but  is  too  titaniferous  to  be  valuable.  It  is  a  lenticular 
mass  in  olivine-gabbro,  and  is  again  referred  to  under  2.03.11. 
A  large  ore  body  has  been  reported  from  Costillo  County,  in 
limestone  (Census  Report)  or  syenite  (Rolker).  In  Gunnison 
County,  at  the  Iron  King  and  Cumberland  mines,  excellent 
ore  occurs  in  quartzites  and  limestones,  called  Silurian.  At 
Ashcroft,  near  Aspen,  high  up  in  the  northern  side  of  the  Elk 
Mountains,  is  a  great  bed  or  vein  of  magnetite  in  limestones 
of  Carboniferous  age  with  abundant  eruptive  rocks  near.  It 
is  thought  by  Devereux  to  be  altered  pyrite.  Stiy,  pyrite  is  a 
common  thing  with  magnetite  elsewhere.  There  are  other 
smaller  deposits  in  Bowlder  County,  and  elsewhere  in  the  State. ^ 

^  H.  S.  Chase,  "Southern  Magnetites  and  Magnetic  Separation,"  Trans. 
Amer.  Inst.  Min.  Eng.,  XXV.,  551-557,  1896.  W.  C.  Kerr,  Geology  of  North 
Carolina,  1875,  364.  J.  P.  Kimball,  "On  the  Magnetite  Belt  at  Cranberry, 
N.  C,"  etc.,  Amer.  Geol.,  XX.,  299-312,  1897.  H.  B.  C.  Nitze,  "Notes  on 
the  Magnetites  of  Southwestern  Virginia  and  the  Contiguous  Territory  of 
North  Carolina,"  Trans.  Amer.  Inst.  Min.  Eng.,  XX.,  174,  and  discussion, 
185.  "The  Magnetic  Iron  Ores  of  Ashe  Co.,  N.  C,  Idem,  XXL,  260. 
"  Magnetic  iron  Ore  in  Granville  Co.,  N.  C,"  Eng.  ajid  Min.  Jour.,  April 
23,  1892,  p.  447.  B.  Willis,  Tenth  Census,  XV.,  325;  Eng.  and  Min.  Jour., 
Jan.  7,  1888.     Kerr  and  Hanna,  "  Ores  of  North  Carolina,"  1893. 

^  R.  Chauvenet,  "Papers  on  Iron  Prospects  of  Colorado,"  A7in.  Reps. 
Colo.  State  School  of  Mines,  1885  and  1887;  also  Trans.  Amer.  Inst.  Min. 


MAGNETITE  AND  PYRITE.  171 

2.03.09.  In  Wyoming  an  immense  mass  of  titaniferous  mag- 
netite is  known  near  Chugwater  Creek.  It  is  more  fully 
described  under  Example  13,  with  which  type  of  ore  body  it 
belongs. 

2.03.10.  Example  12e.  California  Magnetite.  Beds  of  mag- 
netite of  lenticular  shape  in  metamorphic  slates  and  limestones 
on  the  western  slope  of  the  Sierra  Nevada.  Others  of  different 
character  are  also  known.  In  Sierra  and  Placer  counties  lenses 
of  excellent  ore  are  found,  accompanying  an  extended  stratum 
of  limestone  in  chlorite  slate.  A  great  ore  body  of  magnetite 
described  as  a  vein  has  lately  been  reported  from  San  Bernard- 
ino Count}^  It  is  said  to  be  from  30  to  150  feet  thick,  and  to 
lie  between  dolomitic  limestone  and  syenite.^  A  great  bed  of 
a  kind  not  specified  is  reported  from  San  Diego  County. '^ 

2.03.11.  Example  13.  Masses  of  titaniferous  magnetite  in 
igneous  rocks  which  are  most  often  gabbros  or  related  types. 
General  comments  were  made  upon  these  in  1.06,14  and  1.06.16. 
In  many  cases  such  ore  bodies  seem  undoubtedly  to  be  exces- 
sively basic  segregations  of  fused  and  cooling  magmas.  Whether 
the  tendency  of  these  early  crystallizations  to  concentrate  is  due 
to  Soret's  principle,  to  magnetic  currents  or  attractions,  or  to 
the  high  specific  gravity  of  the  mineral  which  might  cause  it 
to  sink  in  the  magma,  is  perhaps  not  always  clear,  for  all  these 
explanations  have  been  suggested.  The  masses  are  not  yet  of 
practical  value  in  North  America,  and  hence  are  not,  strictly 
speaking,  ores;  but  no  one  familiar  with  their  size  and  amount 
can  resist  the  conviction  that  they  will  ultimately  be  utilized. 
The  commonest  rocks  forming  the  walls  are  gabbros,  norites, 
diorites  or  peridotites,  all  of  which  are  close  relatives.  Later 
metamorphism,  such   as   mountain-making    processes  and  the 

Eiig.,  Denver  meeting,  1889.  Rec.  W.  B.  Devereux,  "Notes on  Iron 
Prospects  in  Pitkin  County,  Colorado,'  Trans.  Amer.  Inst.  Min.  Eng., 
XII.,  608.  B.  T.Futnam,  Tenth  Census,  Vol  XV.,  i>.  4:72.  Rec.  C.  M. 
Rolker,  "Notes  on  Iron  Ore  Deposits  in  Colorado,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XIV.,  266.     Rec. 

^  A7in.  Rep.  State  Mineralogist,  1889,  p.  235.  • 

'  Ibid.,  1889,  p.  154.  J.  R.  Browne,  "Mineral  Resources  West  of  the 
Rocky  Mountains,"  1868.  C.  King  and  J.  D.  Hague,  "Mineral  Resources 
West  of  the  Rocky  Mountains,"  1874,  p.  44.  H.  G.  Hanks  and  W.  Irelan, 
Ann.  Reps.  State  Mineralogist,  California.  (Very  little  on  iron. )  F.  von 
Richthofen,  private  reports  quoted  in  Tenth  Census,  Vol.  XV.,  p.  495. 
J.  D   Whitney,  G-zol.  Survey  of  Cal. ,  Vol.  I. 


172  KEMP'S  ORE  DEPOSITS. 

like,  sometimes  give  the  wall  rock  a  gneissic  structure  and 
stretch  out  the  ore  into  apparent  beds.  The  ores  have  some 
characteristic  peculiarities  of  chemical  and  mineralogical  com- 
position. As  a  rule,  although  not  invariably,  they  are  low  in 
sulphur  and  phosphorus.  On  analysis  they  almost  always 
afford  small  percentages  of  vanadium,  chromium,  nickel  and 
cobalt.  They  may  be  so  rich  in  alumina  and  magnesia  as  to 
indicate  the  presence  of  spinel.  In  fact,  one  variety  of  these 
ores,  that  is  found  near  Peekskill,  N.  Y.,  and  at  Routivara,  in 
Sweden,  is  an  aggregate  of  spinel  and  titaniferous  magnetite. 
Ores  of  this  variety  show  genetic  relations  with  some  deposits 
of  emery  and  corundum.  The  pig  iron  afforded  by  the  titanif- 
erous ores  has  certain  excellencies  peculiar  to  itself  that  may 
be  due  to  one  or  more  of  the  above  ingredients.^ 

Many  years  ago  T.  S.  Hunt  recognized  the  fact  that  the 
titaniferous  ores  of  Canada  and  the  Adirondacks  were  limited 
to  the  labradorite  rocks  of  the  Norian  or  Upper  Laurentian 
series.  It  is  now  known  that  they  may  occur  both  in  anor- 
thosites  and  in  basic  gabbros.  The  ore-bodies  are  of  enormous 
size  on  the  lower  St.  Lawrence  (Bay  St.  Paul),  on  the  Sague- 
nay  River,  and  near  Lake  Sandford,  in  the  heart  of  the  Adiron- 
dacks. Smaller,  but  still  very  large  masses,  are  known  in  Que- 
bec, north  of  Montreal ;  in  Ontario,  north  of  Kingston ;  in  West- 
port  and  Elizabethtown,  N.  Y.,  and  in  several  other  places  not 
far  from  the  national  boundary.^ 

^  The  chemical  characters  are  discussed  by  J.  F.  Kemp  in  a  paper  on 
"The  Titaniferous  Iron  Ores  of  the  Adirondacks,"  Nineteenth  Ann.  Rep. 
Dir.  U.  S.  Geol.  Survey,  Part  III. ,  p.  377.  A  detailed  review  of  titanifer- 
ous ores  the  world  over,  by  the  same  writer,  will  be  found  in  the  School 
of  Mines  Quarterly,  July  and  November,  1899.  All  the  analyses  known 
to  be  published  to  date  are  compiled. 

^  On  the  Canadian  ores  see:  F.  D.  Adams,  "  Ueber  das  Norian  oder 
Ober-Laurentian  von  Canada,  Neues  Jahrbueh,  Beilage  Band,  VIII.,  410; 
an  English  translation  will  be  found  in  the  Canadian  Record  of  Science, 
1894,  169;  1895,  Jan.,  p.  1,  July,  p.  1.  "On  the  Igneous  Origin  of  Certain 
Ores,"  Proc.  General  Mining  Association  of  the  Province  of  Quebec,  Jan. 
12,  1894.  E.  3r.  Chapman,  "On  Some  Iron  Ores  of  Central  Ontario," 
Trans.  Royal  Soc.  of  Can.,  1885,  9.  See  also  Idem,  1884,  159,  R.  W.  Ells, 
Geol.  Survey  of  Canada,  1888-89,  14K.  B.  J.  Harrington,  Idem,  1873-74, 
227.  T.  S.  Hunt,  Idem,  1847,  59;  1867,  212.  F.  J.  Pope,  "Titaniferous 
Ores  of  Ontario,"  Trans.  Amer.  Inst.  Min.  Eng.,  May,  1899.  On  the  ores 
in  New  York  see:  E.  Emmons'  Report  on  the  Second  District,  N.  Y.,  State 
Survey,  244,  1842.     J.  F.  Kemp,  "The  Titaniferous  Iron  Ores  of  the  Adi- 


MAGNETITE  AND  P TRITE.  173 

The  ores  near  Peekskill  are  low  in  titanic  oxide,  not  ranging 
above  four  per  cent.,  but  they  are  extremely  rich  in  alumina, 
and  attention  was  first  directed  to  them  by  J.  P.  Kimball,  on 
account  of  this  ingredient.  They  constitute  excessively  basic 
developments  in  the  norites  of  the  Cortlandt  series  of  gabbroic 
rocks,  that  cover  about  twenty-five  square  miles  on  the  Hudson 
River.  They  are  also  present  as  small,  separate  dikes.  They 
consist  of  spinel,  magnetite,  corundum,  garnet  and  occasional 
sillimanite,  and  are  remarkably  close  parallels  with  some  results 
of  artificial  experiments  obtained  by  Josef  Morozewicz.  They 
have  been  utilized  for  emery  and  are  near  relatives  in  a  geo- 
logical way  to  some  deposits  of  corundum  and  emery.  ^ 

A  very  curious  and  interesting  knob,  or  boss,  of  peridotite  is 
exposed  at  Iron  Mine  Hill,  Cumberland,  R.  I.,  that  is  so  en- 
riched with  titaniferous  magnetite  as  to  receive  attention  as  an 
ore.  It  protrudes  through  mica  schists  and  is  closely  akin  to 
the  Swedish  one  at  Taberg,  as  was  recognized  many  years  ago 
by  M.  E.  Wadsworth.' 

A  belt  of  titaniferous  ores  traverses  New  Jersey  and  affords 
magnetites  of  moderate   percentages  of  TiO-2.^     Several  belts 

rondacks,"  Nineteenth  Ann.  Rep.  Director  U.  S.  Geol.  Survey,  377,  1899. 
Also  Fifteenth  Ann.  Report  of  N.  Y.  State  Geologist,  608,  1898.  G. 
W.  Maynard,  "The  Iron  Ores  of  Lake  Champlain,"  Jour.  Brit.  Iron  and 
Steel  Inst.,  1874.  A.  J.  Rossi,  "Titaniferous  Ores  in  the  Blast  Furnace," 
Trans.  Amer.  Inst.  Min.  Eng.,  XXI.,  832,  1893.  "  The  Smelting  of  Titan- 
iferous Ores,"  The  Iron  Age,  Feb.  6  and  20,  1896. 

^  J.  D.  Dana,  Amer.  Jour.  Sci.  Further  notes  by  G.  H.  Williams,  Idem, 
Feb.,  1887,  194.  J.  P.  Kimball,  Amer.  Chemist,  IV.,  1874,  321  ;  Trans. 
Amer.  List.  Min.  Eng.,  IX.,  19,  1880.  Their  geological  relations  will  be 
more  fully  described  in  a  forthcoming  paper  bj^  J.  F.  Kemp  and  M.  B. 
Yung.  On  the  artificial  production  of  these  ore  mixtures,  see  Josef 
Morozewicz,  Tschei^maks  Min.  u.  Petr.  Mitth.,  "On  the  Related  Swedish 
Ores."  W.  Petterson,  Geol.  Foren.  iri Stockholm  Forhandl.,  XV.,  45,  1893. 
Hj.  Sjogren,  Idem,  55  and  140. 

»  M.  E.  Wadsworth,  "  Lithological  Studies,"  Bull.  Mus.  Comp.  Zool. 
Harvard  College,  VII. ,  1881,  183.  A  later  note  will  be  found  in  the  Bulletin 
Amer.  Iron  and  Steel  Association,  Nov.  20,  1889.  See  also,  A.  L.  HoUey, 
Trans.  Amer.  Inst.  Min.  Eng.,  YI.,  224,  1877.  C.  T.  Jackson,  Geological 
Survey  of  Rhode  Island,  53,  1840.  N.  S.  Shaler,  Sixteenth  Ann.  Rep. 
U.  S.  Geol.  Survey,  II.,  321.  Bull.  Mus.  Comp.  Zool,  Harvard  College, 
XVI.,  185.     B.  Willis,  Tenth  Census,  XV.,  567. 

^  On  New  Jersey,  see  the  Annual  Reports  of  the  State  Geologist  as 
follows:  1873,  53,  55;  1875,  35;  1876,  54;  1877,  49;  1878,  99,  100;  1879,62, 
67,  76;  1880,  125.     R.  W.  Raymond,   Trans.  Amer.  Inst.  Min.  Eng.,  XXI., 


174  KEMP'S  ORE  DEPOSITS. 

occur  in  North  Carolina.^  The  wall  rocks  have  not  been  as 
yet  accurately  determined  in  either  State.  In  the  extreme 
northeastern  corner  of  Minnesota,  on  Mayhew  Lake,  and  at  other 
points  within  the  huge  area  of  gabbros  in  this  State,  the  ores 
are  known,  and  some  small  amount  of  work  has  been  expended 
on  them.^  Titaniferous  ore  has  been  described  by  Arnold 
Hague  as  forming  great  dikes  in  granite  on  Chug  water  Creek, 
Wyo.  Olivine-gabbro  and  anorthosite  are  in  the  neighbor- 
hood, and  have  been  determined  as  the  wall  rock  of  at  least  one 
mass  of  ore  by  B.  F.  Hill/  The  rock  was  collected  by  W.  G. 
Knight.  The  ores  are  also  known  in  at  least  three  plaaes  in 
Colorado.  One  is  in  Fremont  County,  at  the  so-called  Iron 
Mountain,  which  is  situated  about  fifty  miles  west  of  Pueblo, 
in  the  Wet  Mountain  valley,  on  a  tributary  of  Grape  Creek. 
A  sample  of  rock  believed  to  have  come  from  the  walls  has 
been  determined  by  J.  F.  Kemp  to  be  an  olivine-gabbro.*  An- 
other locality  is  Caribou  Hill  in  Boulder  County/  and  a  third 


1892,  375.  B.  F.  Fackenthal,  lde7n,  279.  Isidor  Walz,  Amer.  Chemist, 
June,  1876,  453.  The  Church  mine  on  Schooley's  Mountain  is  the  best 
known  one. 

*  On  North  Carolina,  see  North  Carolina  Geol.  Survey,  II.,  1893,  181. 
J.  P.  Lesley,  "Notes  on  the  Titaniferous  Iron-ore  Belt  near  Greensboro, 
N.  C,"  Proc.  Amer.  Phil.  Soc,  XII.,  1871,  139.  H.  B.  C.  Nitze,  Bulletin 
I.,  N.  C.  Geol.  Survey.  Bailey  Willis,  "On  the  Dannemora  Mine,"  Tenth 
Census,  XV.,  310. 

^  W.  S.  Bayley,  "Peripheral  Phases  of  the  Great  Gabbro  Mass  of  North- 
eastern Minnesota,"  Jour.  Geol.,  Vol.  I.,  p.  818.  See  also,  for  notes  on 
their  petrography.  Idem,  Vol.  III.,  p.  1.  C.  R.  Van  Hise,  Bull.  Geol.  Soc. 
Amer.,  VII.,  1895,488.  N.  H.  Winchell.  Tenth  Ann.  Rep.  Minn.  Geol. 
Survey,  1882,  85.     N.  H.  and  H.  V.  Winchell,  Bulletin  VI,  Idem,  136.     M. 

E.  Wadsworth,  Bulletin  II,  Idem,  63,  73. 

^  Arnold  Hague,   U.  S.   Geol.  Explor.  Fortieth  Parallel,  II.,  12,  1877. 

F.  V.  Hay  den,  U.  S.  Geol.  and  Geogr.  Survey,  Territories,  1870,  14.  B.  F. 
Hill,  School  of  Mines  Quarterly,  July,  1899.  W.  G.  Knight,  Bull.  XIV. 
Wyo.  Agric.  Experiment  Station,  177,  1893.  Howard  Stansbury,  Ex- 
ploration and  Survey  of  the  Valley  of  the  Great  Salt  Lake,  1852,  266.  F. 
Zirkel,  U.  S.  Geol.  Explor.  Fortieth  Parallel,  VI.,  107. 

*  F.  M.  Endlich,  U  S.  Geol.  and  Geogr.  Survey  of  the  Territories,  1873, 
333.     B.  T.  Putnam,  Tenth  Census,  XV.,  472. 

®  Regis  Chauvenet,  "Notes  on  Iron  Prospects  in  Northern  Colorado," 
Biennial  Rept.  of  the  Colo.  State  School  of  Mines,  1886, 16.  B.  T.  Putnam, 
Tenth  Census,  XV.,  476. 


MAGNETITE  AND  PYUITE.  175 

is  in  the  Cebolla  district,  Gunnison  County/  where  the  amount 
is  reported  to  be  large.  The  ores  in  basic  nepheline  rocks  in 
BraziP  are  the  only  others  in  the  Western  Hemisphere.  The 
Swedish  and  Norwegian  ores  are  similar  in  their  geological  rela- 
tions to  the  several  American  types,  viz. :  those  at  Ekersund 
and  Soggendahl,^  to  the  ores  of  Quebec  and  the  Adirondacks; 
those  at  Routivara*  to  the  aluminous  ores  of  the  Cortlandt 
series;  the  Taberg^  ore  is  like  that  at  Cumberland,  R.  I. ;  and 
the  Alno^  occurrence  resembles  the  Brazilian  type.  The  titan- 
iferous  iron  sands  will  be  referred  to  under  magnetite  sands. 

2.03.12.  Example  14.  Cornwall,  Pa.  Deposits  of  soft 
magnetite,  resting  against  igneous  dikes  and  associated  with 
green,  pyritous  shales,  Si luro- Cambrian  limestone  and  Trias- 
sic  sandstone.  These  ore  bodies  are  to  be  classed  among  the 
largest  ever  mined.  They  form  three  hills  extending  in  an  east 
and  west  direction,  and  called  respectively  Big  Hill,  Middle 
Hill  and  Grassy  Hill.  As  the  accompanying  contour  map 
shows,  Big  Hill  is  the  highest  and  narrowest,  while  Middle 
Hill  contains  the  most  ore.  The  hills  lie  just  at  the  southeast- 
ern edge  of  the  Great  Valley,  and  are  six  miles  from  the  flour- 

^  Regis  Chauvenet,  "Iron  Resources  of  Gunnison  Co. ,"  ^mer.  Rep.  Col. 
State  School  of  Mines,  1887,  18.  "Iron  Resources  of  Colorado,"  Trans. 
Amer.  Inst.  Min  Eng.,  XVIII.,  272.  Arthur  Lakes,  "The  Great  Cebolla 
River  Deposits,"  Colliery  Engineer,  XVI.,  267,  1896. 

^O.  A.  Derby,  "Magnetite  Ore  Districts  of  Jacupiranga  and  Ipanema, 
Sao  Paulo,  Brazil,"  Amer.  Jour.  Sci.,  April,  1891,  311. 

*  T.  Dahl,  F6rhandl.  videnskabs  Natm.  i.  Stockholm,  1863.  D.  Forbes, 
Chem.  News,  December  11,  1868,  275.  S.  Forbes,  Jour.  Brit.  Iron  and 
Steel  Inst,  1874,  131.  Th.  Kjerulf,  Nyt.  Magazinfor  Natv.,  XXVII.,  1883. 
H.  Rosenbusch,  Idem.  T.  C.  Thomassen,  Idein,  XXIV.,  287.  C.  F.  Kol- 
derup,  Bergen's  Museum's  Aarbog.  in  Stockholm,  1896,  159.  Rec.  H.  H. 
Reusch.  Oeol.  Foren  in  Stockholm,  1877,  197 ;  Neues  Jahrbuch.  1878.  J.  H. 
L.  Vogt.  Idem,  XIII.,  476,  683,  XIV.,  211;  Geological  Magazine,  IX..  82; 
Neues  Jahrbuch,  1893,  II.,  69;  Zeitschr.  fur  prakt.  Geologic,  January,  1893, 
6;  October,  1894,  384;  Archiv.  fur^Mathem.  og  Naturvidenskab,  Kristiania, 
X.  and  XII.,  1887.  The  papers  of  Kolderup  and  Vogt  are  of  chief  value 
for  reference. 

*  W.  Petterson,  Geol.  Foren.  i.  Stockholm,  XV.,  45,  1893;  (Neues  Jahr- 
buch, 1894,  I.,  88) ;  H.  Sjogren,  Idem,  XV.,  55,  140,  1893;  (Neues  Jahrbuch, 
1894,  I.,  88). 

»  A.  Sjogren,  Geol.  Foren.  i.  Stockholm,  III.,  42, 1876;  (Neiies  Jahrbuch 
1876,  434).  A.  E.  Tornebohm,  Idem,  V.,  610;  Neues  Jahrbuch,  1882,  II.,  66. 
J.  H.  L.  Vogt,  Zeitschrift  fur  prakt.  Geologic,  January,  1893,  8. 

«  A.  G.  Hoegbom,  Geol.  Foren.  i.  Stockholm,  XVII.,  100,  214,  1895. 


176  KEMP'S  ORE  DEPOSITS. 

ishing  little  city  of  Lebanon.  The  geological  section  (Fig.  53) 
illustrates  the  position  of  the  strata.  The  Siluro-Cambrian 
series  is  cut  by  an  immense  diabase  dike  near  its  southeastern 
limit,  and  on  the  south  side  of  the  dike  which  forms  the  north- 
ern rampart  of  the  three  hills  lies  the  ore.  The  ore  is  a  soft, 
rather  earthy  magnetite,  which  occasionally  shows  octahedra. 
While  richer  and  purer  on  the  original  weathered  surface,  it  is 
now  interlaminated  and  closely  involved  with  layers  of  limey 
shales  which  contain  pyrite,  at  times  in  beautiful  crystals. 
Most  of  the  ore  is  merchantable  raw,  but  large  quantities  are 
so  low  from  this  admixture  of  shales  that  they  are  being  saved 
for  possible  future  magnetic  concentration.  The  presence  of 
the  pyrite  makes  it  necessary  to  roast  all  the  raw  ore  before 

■      1     I       .1 


« 


III  I 

1  ? -I-...  I  I       ^         I  §'M 


^cale  of  Miles. 


Fig.  53. — Section  along  Cornwall  Railroad  from  Lebanon  to  Miner's  Village. 
After  E.  V.  d'Inmlliers,  Amer.  Inst.  Min.  Eng.,  XIV.,  898,  1886. 

smelting,  but  the  phosphorus  is  so  low  that  Bessemer  pig  is  the 
chief  resulting  product. 

Big  Hill  differs  from  the  others  in  structure.  The  northern 
dike  with  a  steep  southerly  dip  has  an  offsetting  and  very 
heavy  branch  to  the  southwest  which  forms  with  it  a  great 
trough  or  basin  so  far  as  one  can*  see.  The  bottom  of  the  ore 
has  been  reached  by  one  rather  shallow  hole,  but  it  seems  quite 
certain  that  the  dikes  will  come  together  at  a  point  indicated  by 
the  several  dips.  The  surface  of  the  southerly  branch  is 
strongly  corrugated.  The  ore  of  Middle  HiH  extends  to  a 
greater  distance  south  from  the  dikes  than  that  of  Big  Hill,  and 
is  cut  by  one  small  and  linimportant  offset  of  trap  that  is  two  or 
three  feet  across.     At  the  western  end  of  the  workings,  lime- 


178  KEMP'S  ORE  DEPOSITS. 

stoDO  is  quite  thick  and  in  good  exposure.  It  reaches  well  over 
to  Grassy  Hill.  Grassy  Hill  is  smaller,  and  is  much  less  devel- 
oped than  either  of  the  others.  E.  V.  d'Invilliers  has  empha- 
sized the  important  point  that  the  dip  of  the  ore  in  Big  Hill  is 
southwest  at  such  an  angle  as  to  bring  it  below  the  Middle 
Hill  bed,  and  that  this  latter  also  dips  below  the  limestone  and 
the  Grassy  Hill  beds.  Such  being  the  case,  enormous  reserves 
must  lie  under  the  two  western  hills.  The  depths  of  the  sev- 
eral bore  holes  given  on  the  map  and  all  in  ore  indicate  its 
presence  in  very  great  amount,  but  it  is  important  to  show  in 
this  connection  the  absence  of  faults,  for  the  map  of  Bailey 
Willis  notes  their  presence,  and  observations  of  the  writer  cor- 
roborated their  existence. 

The  pyrite  in  the  calcareous  shales  is  occasionally  replaced  by 
chalcopyrite  in  irregular  nodules  or  veinlets.  The  presence  of 
copper  was  early  noted,  and  some  mining  was  done  for  it  near 
the  surface.  Fine  museum  specimens  of  moss-copper,  azurite, 
malachite,  etc.,  were  afforded.  Even  during  the  earlier  iron- 
mining  some  copper  ore  was  set  aside  as  a  small  by-product. 
Copper  is  still  present  in  the  mine-water,  for  bright  shovels 
left  in  it  become  coated,  and  the  bones  of  dead  animals  thrown 
out  on  the  ore  banks,  as  well  as  chips  of  wood,  etc.,  become 
tinted  a  bright  green. 

Much  difference  of  opinion  has  prevailed  about  the  age  and 
geological  relations  of  these  ores.  Some  have  thought  them 
Mesozoic  and  a  part  of  the  Triassic,  while  others,  and  notably 
J.  P.  Lesley,  have  regarded  them  as  belonging  to  the  Siluro- 
Cambrian  series  and  analogous  to  the  limonites  of  the  Great 
Valley,  but  metamorphosed.  The  great  trap  dikes  afford  the 
most  reasonable  explanation  or  cause  of  the  change,  and  to  these 
may  be  referred  the  alteration.  The  apparent  origin  of  many 
Siluro- Cambrian  limonites  from  the  hydration  and  oxidation  of 
pyritous  shales  and  schists  gives  much  support  to  this  view, 
and  the  association  of  limestone  with  the  ore  and  the  general 
stratigraphical  relations  are  hard  to  explain  in  any  other  way.^ 

^  E.  V.  d'Invilliers,  "Cornwall  Iron  Ore  Mines,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XIV.,  873.  Rec.  Lesley  and  d'Invilliers,  Ann.  Rep.  Second 
Penn.  Geol.  Survey,  1885,  491.  Eec.  J.  P.  Lesley,  Final  Rep.,  I,  351,  1892. 
T.  S.  Hunt,  "The  Cornwall  Mines,"  etc.,  Trans.  Amer.  Inst.  Min.  Eng.. 
IV.,  319.  H.  D.  Rogers,  First  Penn.  Geol.  Survey,  II.,  718.  B.  Willis,  Tenth 
Cenms,  XV.,  223. 


MAGNETITE  AND  P TRITE.  179 

The  total  production  to  April,  1894,  is  stated  by  Mr.  Boyd, 
the  superintendent  of  the  mines,  to  be  upward  of  12,000,- 
000  tons,  while  an  annual  output  of  800,000  can  be  easily  main- 
tained. The  ore  varies  from  40  to  55%  Fe.  It  almost  never  con- 
tains as  much  as  0.02  P,  but  runs  up  to  4%  S.  It  is  also  sil- 
iceous. 

2.03.13.  Several  other  mines  of  somewhat  related  character 
to  the  Cornwall  deposits  are  known  along  the  edges  of  this 
Triassic  belt,  and  associated  with  its  trap  intrusions.  The 
mining  districts  lie  near  its  north  and  south  boundaries,  and 
not  far  from  its  contacts  with  the  older  rocks.  On  the  north 
side  from  east  to  west  there  are  the  Boyertown  (Berks  County), 
the  Fritz  Island  and  the  Wheatfield,  near  Reading,  and  finally 
the  Dillsburg  in  York  County,  west  of  the  Susquehanna.  On 
the  south  side  in  the  same  order  are  the  French  Creek,  St. 
Mary's  and  the  Jones,  all  quite  near  together  and  nearly  south 
of  Reading.  Of  these  the  Boyertown  mines  have  been  most 
worked.^  The  Cornwall  mines  are  between  the  Wheatfield  and 
the  Dillsburg.  At  the  Boyertown  mines  the  ore  lies  both 
between  a  brecciated  limestone  and  Mesozoic  sandstone  and 
wholly  within  the  limestone,  but  trap  dikes  are  not  lacking.  At 
Fritz  Island  the  ore  is  entirely  enclosed  in  limestone,  and  is 
penetrated  by  a  trap  dike.  In  the  Wheatfield  mines  the  same 
brecciated  limestone  appears,  and  has  the  ore  intimately  asso- 
ciated with  it.  On  both  occurs  the  Mesozoic  sandstone,  and 
the  succession  is  five  times  repeated  by  faulting.  The  usual 
trap  penetrates  the  ore.  The  French  Creek  and  St.  Mary's 
mines  are  unique  in  that  they  are  contained  in  gneiss.  They 
are  famous  sources  of  fine  crystals  of  pyrite,  chalcopyrite  and 
other  minerals.  The  Jones  mine  exhibits  the  ore  between  trap 
and   limestone,  the  trap  being  over  the  ore  in  the  North  pit  and 


*  P.  Fraser,  "Study  of  the  Specular  and  Hematite  Ores  of  Iron  of  the 
New  Red  Sandstone  in  York  County,  Pa,"  Trans.  Amer.  Inat.  Min.  Eng., 
v.,  132.  Also  Penn.  Geol.  Survey,  Rep.  CC.  205,  217.  H.  Hoefer,  "Die 
Kohlen  und  Eisenerzlagerstatten  Nord  Amerika's,"  241.  Also  Penn. 
Survey,  Rev.  C2.  E.  V.  d'Invilliers,  "Cornwall  Iron  Ore  Mines,"  Trans. 
Amer.  Inst.  Min.  Eng.,  XIV..  873.  Rec.  Lesley  and  d'lnvilliers.  Ann. 
Rep.  Second  Penn.  Survey,  1885.  J.  P.  Lesley,  Final  Report.  Vol.  L, 
p.  351,  1802  Fee.  T.  S.  Hunt.  "The  Cornwall  Mines,"  etc.  Trans. 
Amer.  Inst.  Min  Eng..  IV.,  319  H.  D.  Rogers.  First  Penn.  Geol.  Survey, 
II.,  718.     B.  Willis.  Tenth  Census,  Vol.  XV.,  p.  223.     Rec. 


180  KEMP'S  ORE  DEPOSITS. 

under  it  in  the  south.  A  green  shale  is  also  met  here,  as  in- 
deed in  most  of  the  other  localities,  although  not  specially  men- 
tioned. At  Dillsburg  th^  evidence  against  the  Triassic  age 
of  the  ores  is  less  positive,  and  upon  this  occurrence  Fraser  has 
based  a  strong  argument  for  the  latter  view.  Triassic  sand- 
stone at  times  forms  both  walls,  although  there  are  instances 
where  limestone  appears  as  the  foot.  In  all  these  localities  the 
presence  of  copper  is  notable.  It  and  the  magnetic  or  metamor- 
phosed condition  of  the  ore  are  probably  referable  to  the  trap. 

2.03.14.  Example  14a.  Iron  County,  Utah.  Beds  of  mag- 
netite and  hematite  bearing  evidence  of  being  metamorphosed 
limonite,  in  limestones  of  questionable  Silurian  age,  and  asso- 
ciated with  eruptive  rocks  described  as  trachyte.  The  lime- 
stones have  been  much  upturned,  metamorphosed,  and  pierced 
bj^  dikes  and  eruptive  masses.  The  ore  forms  great  projecting 
ridges  and  prominent  outcrops,  locally  called  "blow-outs.'' 
The  usual  lenticular  shape  is  not  lacking.  Thej^  occur  over 
an  area  of  fifteen  by  five  miles,  and  are  in  the  southern  end  of* 
the  Wasatch  Mountains.  The  samples  show  rich  ores,  which 
at  times  exceed  the  Bessemer  limit  of  phosphorus.  In  the  Star 
district  the  ore  apparently  lies  between  the  quartzite  and  gran- 
ite. Hematite  occurs  in  large  amount,  as  does  quartz,  while 
some  streaks  have  large  crystals  of  apatite.  The  importance 
of  the  deposits  lies  in  the  future.  They  are  the  largest  in  the 
West,  and  are  interesting  in  their  bearing  on  the  general  origin 
of  the  magnetite.  Coal,  not  proved  to  be  good  for  smelting,  is 
near,  but  centers  of  iron  consumption  are  XQxy  far  away.^ 

2.03.15.  Example  15.  Magnetite  sands.  Beds  of  magnetite 
sands  concentrated  on  beaches  or  bars  by  waves  and  streams. 
The  magnetite  has  been  derived  from  the  weathering  of  igne- 
ous and  metamorphic  rocks  through  which  it  is  everywhere 
distributed.  When  in  the  sand  of  a  sea  beach,  it  and  other 
heavy  minerals  tend  to  become  concentrated  by  the  sorting 
action  of  the  waves.  They  resist  the  retreating  undertow  better 
than  lighter  materials.     Such  deposits   are  very  abundant  at 

*  W.  P.  Blake,  "Iron  Ore  Deposits  of  Southern  Utah/'  Trans.  Amer. 
Inst.  Min.  Erig.,  XIV,,  809.  J.  S.  Newberry,  "Genesis  of  Our  Iron  Ores," 
School  of  Mines  Quarterly,  March,  1880.  Rec.  Engineei'ing  and  Mining 
Journal,  April  23,  1881,  p.  286;  Proe.  National  Academy,  1880.  B.  T. 
Putnam.  Tenth  Census,  Vol.  XV.,  486.     Rec. 


MAGNETITE  AND  PYRITE.  181 

Moisie,  on  the  St.  Lawrence,  below  Quebec,  and  in  the  United 
States  are  known  in  smaller  developments  on  Lake  Cbamplain ; 
at  Quogue,  L.  L;  on  Block  Island;  in  Connecticut;  along  the 
Great  Lakes,  and  on  the  Pacific  coast.  Grains  of  garnet,  oli- 
vine, hornblende,  etc.,  minerals  of  high  specific  gravity,  are 
also  in  the  sands.  Many  are  too  high  in  titanium  to  be  of  use, 
but  there  is  no  more  difficulty  in  their  concentration  than  in 
that  of  artificially  crushed  ore.  In  Brazil  and  New  Zealand 
they  have  attracted  attention.^ 

2.03.16.  On  the  Origin  of  Magnetite  Deposits.  It  is  im- 
portant to  note  that  magnetite  deposits  are  almost  always  in 
metamorphic  rocks,  which  owe  their  character  to  r^ional 
metamorphism  or  to  the  neighborhood  of  igneous  rocks  (Penn- 
sylvania and  Utah).  Gneisses  form  the  commonest  walls,  but 
so-called  norites,  or  gabbros,  and  crystalline  limestones  also 
contain  them*  Where  there  is  lamination  or  foliation  the  mag- 
netite conforms  to  it.  As  the  history  of  the  metamorphic  rocks 
is  so  often  uncertain,  the  magnetites  share  the  same  doubt. 
In  igneous  rocks  magnetite  is  the  most  widely  occurring  of 
the  rock-making  minerals.  In  all  explanations  the  prevailing 
lenticular  shape,  ihe  general  arrangement  in  linear  order,  and 
the  existence  of  great  beds  must  be  considered.  The  shape  is 
ver}'  similar  to  that  of  deposits  of  specular  hematite,  with 
which  magnetite  is  often  associated.  (Examples  9  and  10.) 
The  following  hypotheses  have  been  advanced  for  the  origin  of 
magnetites:  1.  Intruded  (eruptive)  masses.  This  supposes 
that  the  lenses  have  been  intruded  like  a  trap  dike,  and  have 
then  been  squeezed  and  pinched  apart.  Though  formerly  much 
advocated,  it  is  now  generally  rejected.  2.  Excessively  basic 
portions  of  igneous  rocks.  This  supposes  that  large  amounts 
of  iron  oxide  have  separated  in  the  cooling  and  crystallizing  of 
basic  magmas.  There  are  such  occurrences,  although  seldom, 
if  ever,  pure  enough  or  abundant  enough  for  mining.  The 
titaniferous  magnetite  of  the  Minnesota  gabbros  has  been 
alluded  to  (2.02.25),  and  also  the  Brazilian  ore  and  the  Cum- 

^  T.  S.  Hunt,  Qeol  Survey,  Canada,  1866-69,  261,  262;  quoted  in  Six 
teenthAnn.  Rep.  Dir.  U.  S.  Geol.  Survey,  III.,  50,  51;  Can.  Nat,  VI.,  79. 
A.  A.  Julien,  "The  Genesis  of  the  Crystalline  Iron  Ores,"  Acad  Nat.  Sci., 
Phila. ,  1882,  335 ;  Engineering  and  Mining  Journal  February  2,  1884.  On 
New  Zealand  sands,  E.  M.  Smith.  Proc.  Brit.  Iron  and  Steel  Inst.,  May, 
1896;  Eng.  and  Min.  Jour.,  June  13,  1896,  p.  566. 


182  KEMP'S  ORE  DEPOSITS. 

berland  Hill  (R.  I.)  peridotite.  Should  such  igneous  rocks 
be  subjected  to  regional  metamorphism  and  the  stretching 
action  characteristic  of  it,  the  ore  masses  might  be  drawn 
out  into  lenses.  3.  Metamorphosed  limonite  beds.  This  idea 
has  been  most  widelj^  accepted  in  the  past  It  presupposes 
limonite  beds  formed  as  in  Examples  1  and  2,  which  become 
buried  and  subjected  to  metamorphism,  changing  the  ore  to 
magnetite,  and  the  walls  to  schists  and  gneisses.  Igneous  rocks 
have  apparently  changed  limonites  to  magnetite  at  Cornwall, 
Pa.,  and  in  Utah,  but  such  changes  by  regional  metamor- 
phism are  less  easy  to  demonstrate.  The  limonite  may  have 
resulted  from  the  oxidation  of  lenses  of  pyrite.  4.  Replaced 
limestone  beds,  or  siderite  beds  subsequently  metamor- 
phosed. Such  deposits  may  pass  through  a  limonite  stage. 
The  general  process  is  outlined  under  Example  9c,  as  devel- 
oped by  Irving  and  Van  Hise  in  the  Gogebic  district.  The 
lenticular  deposits  of  siderite  at  the  Burden  mines  (Example 
4)  are  very  suggestive,  and  some  such  original  mass  might  in 
instances  be  metamorphosed  to  magnetite.  5.  Submarine  chem- 
ical precipitates.  This  is  outlined  under  Example  9d,  as  applied 
by  the  Winchells  in  Minnesota.  6.  Beach  sands.  The  lenses 
are  regarded  as  having  been  formed  as  outlined  under  Exam- 
ple 15.  The  same  heavy  minerals  sometimes  occur  with  mag- 
netite lenses  as  are  found  on  beaches.*  7.  River  bars.  This 
regards  the  lenses  as  due  to  the  concentration  of  magnetite 
sands  in  rivers  or  flowing  currents.  Hence  the  overlapping 
lenses,  the  arrangement  in  ranges  or  on  lines  of  drainage, 
and  the  occasional  swirling  curves  found  on  the  feathering 
edges  of  lenses,  as  in  the  Dickerson  mine,  Ferromont,  N.  J.^ 
It  is  also  reasonable  to  suppose  that  lakes  or  still  bodies  of  water 
may  have  occurred  along  such  rivers,  and  have  occasioned  the 
accumulation.  8.  Segregated  veins.  By  this  method  the  iron 
oxide  is  conceived  to  concentrate  from  a  state  of  dissemination 
in  the  walls  by  slow  segregation  in  solution  to  form  the  ore  bodies 
along  favorable  beds.  The  action  is  analogous  to  the  formation 
of  concretions,  and  is  illustrated  on  a  small  scale  by  the   well- 

^  See  also  Dakyns  and  Teall,  Qiiar.  Jour.  Geol.  Sgc,  LXVIII.,  p.  118. 

''See  B.  J.  Harrington,  Can.  Geol.  Survey,  1873,  193;  A.  A.  Julien, 
Phila.  Acad.  Sci.,  1882,  335. 

^  See  H.  S.  Munroe,  School  of  Mines  Quarterly,  Vol.  III.,  p.  43 — an  im- 
portant paper. 


MAGNETITE  AND  P TRITE. 


183 


known  disks  of  pyrite,  or  of  siderite,  that  form  in  clays  and 
shales.  It  is  a  curious  fact,  however,  that  some  magnetites  are 
in  wall  rock  that  hardly  shows  a  trace  of  a  dark  silicate.  The 
lenses  at  Hammondville,  in  the  Lake  Champlain  district,  are 
in  a  white,  or  light- colored  gneissoid  rock,  consisting  of 
quartz,  acidic  plagioclase,  and  a  few  scattered  garnets.  In 
such  surrovindings  segregation  could  not  be  applied,  but  where 
the  walls  are  supplied  with  hornblende  and  other  ferruginous 
minerals,  and  are  reasonably  basic,  it  might  be  advocated. 

Several  other  hypotheses  with  small  claims  to  credibility 
€Ould  be  cited.  They  are  outlined  at  length  in  Bull.  VI., 
Minn.  Geol.  Survey^  p.  224,  but  in  this  place  there  has  been 
no  desire  to  take  up  any  but  those  deserving  serious  attention. 
It  may  be  said  that  while  one  or  the  other  of  the  above  seven 
hypotheses  may  in  instances  be  applied  with  reason,  yet  most 
candid  observers  with  widened  experience  have  grown  less 
positive  in  asserting  them  as  axiomatic. 


ANALYSES  OF  MAGNETITES. 

(Caution  in  interpreting  analyses  is  again  emphasized  as  under  2.01.26.) 


Fe. 

P. 

S. 

TiO,. 

SiO,. 

Al,03. 

Canada  (Rideau  Canal) 

50.23 
49.24 
66.00 
62.10 

63.00 
48.82 
53.75 
42  70 

9.80 

Chateaugay  mines,  N.  Y.,  lump. . 
' '                "        concentrated 

0.029 
0.003 
1.198 

0.621 
0.021 
0.364 
0.135 
0.004 
0.026 
0.044 

0.052 

18.447 

Mineville,  N.  Y.  (Mine  21) 

Orange  County,  N.  Y.   (Forest  of 
Dean)  

0.148 
0.080 

Putnam  County,  N.  Y 



11.75 

3.500 

New  Jersey  (Hibernia) 

Cornwall,  Pa 

0.620 
0.115 

3.411 

Cranberry,  N.  C 64.64 

Colorado  (Calumet)     49  23 

3.85 

' '         (Iron  King) 

58.75 

0.123 
0.120 

Utah  (Iron  County) 

62.60 
60.68 

4.80 
10.87 

California  (Gold  Valley)     . 

2.03.16.  Of  importance  in  connection  with  iron  ore  deposits 
are  the  recent  studies  of  the  distribution  of  phosphorus  along 
certain  lines  in  the  beds,  by  a  knowledge  of  which  it  is  possi- 
ble to  keep  more  valuable  Bessemer  ore  distinct  from  less 
valuable.  Such  lines  have  been  found  in  Michigan,  and  have 
been  called  by  D.  H.  Browne  'Msochemic  lines."    Though  less 


184  KEMP'S  ORE  DEPOSITS. 

marked  at  the  Burden  mines  (Example  3),  the  phosphorus  was 
characteristic  of  certain  varieties  of  the  ore.  Much  work  has 
also  been  done  on  the  same  question  at  Iron  Mountain,  Mo/ 

PYRITE. 

2.03. 17.  Example  16.  Pyrite  Beds,  Beds  (veins)  of  pyrite, 
often  of  lenticular  shape  and  of  character  frequently  analogous 
to  magnetite  deposits,  in  slates  and  schists  of  the  Cambro- 
Silurian  or  Huronian  systems,  and  less  often  in  gneiss  of  the 
Archean.  Slates  are  most  common,  and  gneiss  least  so.  They 
extend  from  Canada  down  the  Appalachians  to  Alabama,  being 
found  at  Capelton,  Quebec ;  Milan,  N.  H. ;  Vershire,  Vt. ; 
Charlemont,  Mass.;  Louisa  County,  Virginia;  Ducktown, 
Tenn.,  and  at  many  points  less  well-known  in  Alabama. 
Anthony's  Nose,  N.  Y.,  the  Gap  mine,  Pennsylvania,  and 
Sudbury,  Ontario,  being  different  geological  relations,  will  be. 
mentioned  under  "Nickel"  with  other  similar  occurrences. 

2.03.18.  The  ore  bodies  lie  interfoliated  in  the  slates  or  schists, 
and  the  different  lenses  often  overlap  and  succeed  each  other  in 
the  footwall,  and  exhibit  all  the  phenomena  cited  under  magne- 
tites. Chalcopyrite  is  usually  present  in  small  amount,  and 
where  the  copper  reaches  3  to  b%  they  are  valuable  as  copper 
ores.  (See  under  "Copper.")  At  present  they  are  of  increas- 
ing importance  as  a  source  of  sulphuric  acid  fumes  for  the 
manufacture  of  vitriol.  Small  amounts  of  lead  and  zinc 
sulphide  are  often  present,  and  rarely  a  little  silver.  Nickel 
and  cobalt  occur,  especially  in  the  pyrrhotitic  varieties.  They 
are  worthless  as  a  source  of  iron.  The  smaller  deposits  of 
auriferous  pyrites  in  the  Southern  States  will  be  mentioned 
under  "Gold." 

2.03. 19.  Some  pyrites  lenses  may  have  accumulated  in  a  way 
analogous  to  the  bog  ore  hypothesis,  cited  under  "Magnetite"  ; 
but  instead  of  the  iron  being  precipitated  as  oxide,  it  has  proba- 
bly come  down  as  sulphide  from  the  influence  of  decaying  or- 
ganic matter,  and  has  subsequently  shared  in  the  metamorphism 
and  solidification  of  the  wall  rock.    At  the  same  time  it  must  be 

'  D.  H.  Browne,  "On  the  Distribution  of  Phosphorus  at  the  Luddington 
Mines,"  etc..  Trans.  Amer.  Inst.  Min.  Eng.,  XVII.,  p.  616.  I.  Olmsted, 
"The  Distribution  of  Phosphorus  in  the  Hudson  River  Carbonates," 
Trans.  Amer.  Inst.  Min.  Eng.,  XVIII.,  p.  252.  W.  B.  Potter,  "Analysis  of 
Missouri  Ore,"  published  in  Mineral  Resources,  1890,  p.  47. 


MAGNETITE  AND  PYRITE.  185 

admitted  to  be  an  obscure  point.  Bj'  many  they  are  thought, 
with  more  reason,  to  have  originated  like  a  bedded  fissure  vein 
whose  overlapping  lenticular  cavities  have  been  formed  by  the 
buckling  of  folded  schists.^  (Cf.  '*Gold  Quartz,"  as  later  de- 
scribed.) The  Ducktown  veins  are  on  lines  of  dislocation  be- 
yond question.  Replacements  of  pinched  beds  of  limestone  are 
always  to  be  considered,  and  the  presence  of  intruded  dikes, 
though  disguised  by  metamorphism.  is  always  to  be  kept  in 
mind. 

2.03.20.  The  excavations  in  some  of  the  mines  in  the  pyrite 
beds  of  Canada,  just  north  of  the  Vermont  line,  have  shown 
dikes  of  granite  in  close  association  with  the  ore.  Thin 
sections  of  the  granite  indicate  that  it  has  suffered  extremely 
severe  dynamic  metamorphism,  for  crushed  and  strained 
crystals  make  up  nearly  all  of  its  substance.  It  is  quite 
probable  that  the  disturbance  which  causes  the  schistosity 
or  slaty  cleavage  of  the  country  rock  likewise  developed  the 
strains  in  the  granite  which  must  thus  have  been  intruded  pre- 
vious to  its  operation.  Before  the  shattering  the  dikes  may 
have  exerted  a  genetic  influence  in  connection  with  the  ore 
body,  but  now  the  ore  is  usually  lean  near  them.  The  ore 
bodies  are  also  cut  by  fine  examples  of  the  trap  (camptonite) 
dikes  which  are  abundant  in  the  Lake  Champlain  Valley. 
Prof.  J.  H.  L.  Vogt,  of  Christiania,  Norway,  has  written 
of  late  regarding  the  origin  of  similar  great  bodies  of  sulphides 
in   Europe,  and  when    they  occur  in   connection   with  rocks, 

'  W.  H.  Adams,  "The  Pyrites  Deposits  of  Louisa  County,  Virginia," 
Trans.  Amer.  Inst.  Min.  Eng.,  XII.,  p.  527.  C.  R.  Boyd,  "The  Utiliza- 
tion of  the  Iron  and  Copper  Sulphides  of  Virginia,  North  Carolina,  and 
Tennessee,"  Trans.  Amer.  Inst.  Min.  Eng.,  XIV.,  p.  81;  Resources  of  S.  W, 
Virginia.  H.  Credner,  "At  St.  Anthony's  Nose,  Hudson  River,"  B.  und 
H.  Zeit.,  1866,  p.  17;  "Pyrite  in  Virginia,  Tennessee,  and  Georgia,"  B.  und 
H.  Zeit.,  1871,  p.  370.  H.  T„  Davis,  Mineral  Resources  of  the  U.  S.,  1885, 
p.  501.  William  Martyn,  Mineral  Resources,  1883-84,  p.  877.  E.  C.  Mox- 
ham,  "The Great  Gossan  Lead  of  Virginia"  (altered  pyrite  in  Carroll 
County),  Trans.  Amer.  Inst.  Min.  Eng.,  XXI.,  p.  133.  A.  F.  Wendt, 
"The  Pyrites  Deposits  of  the  Alleghanies,'  School  of  Mines  Quar- 
terly, Vol.,  VII.,  and  separate  reprint;  also  Engineering  and  Mining 
Journal,  June  5,  1886,  p.  22,  and  elsewhere.  Rec.  H.  A.  Wheeler, 
"Copper  Deposits  of  Vermont,"  School  of  Mines  Quarterly,  IV.,  210. 
Arthur  Winslow,  "Pyrites  Deposits  of  North  Carolina,"  Ann.  Rept.  N.  C. 
Experiment  Station,  1886. 


186  KEMP'S  ORE  DEPOSITS. 

which  though  now  gneissoid,  have  been  originally  igneous,  he 
regards  them  as  basic  segregations  of  an  igneous  magma.  (See 
further  1.06.16.)  Where  they  occur  in  schists  he  attributes 
their  formation  to  ore-bearing  solutions,  penetrating  along 
planes  of  weakness,  and  stimulated  by  neighboring  igneous 
intrusions.  In  some  of  the  instances  cited  the  known  igneous 
intrusions  (as  at  Rammelsberg)  are  at  some  distance,  and  thus 
are  not  directly  associated,  so  far  as  one  can  see,  with  the  oreo 
The  genetic  connection  is  therefore  somewhat  hypothetical. 


2.03.21.  The  relative  importance  of  the  different  kinds  of 
ore  is  shown  by  the  following  tables  for  1880  and  1896.  The 
increase  in  red  hematite  is  due  to  the  Lake  Superior  region, 
and  to  Alabama.  In  the  immediate  future  the  soft  ores  of  the 
Mesabi  district  will  help  to  greatly  swell  the  total,  but  during 
1893-94  there  was  great  depression  in  the  mining  of  iron  ore 
throughout  the  country  : 

Per  cent.  Per  cent. 

1880.  of  Total.  1896.  of  Total. 

Red  hematite 2,512,713  31.51  12,576,288  78.58 

Magnetite «...  .2,390,389  29.98  1,211,526  7.57 

Brown  hematite 2,149,417  26.95  2,126,212  13.28 

Carbonate 922,288  11.56  91,423  0.57 


7,974,806  100.00         16,005,449        100.00 

As  indicating  the  relative  importance  of  the  different  mining 
regions,  the  following  figures  are  of  interest.  No  individual 
State  producing  less  than  100,000  tons  is  given. 

states.  Total  in  \^m.  States.  TotalinlSdQ. 

Michigan 5,706,736  Tennessee 535,484 

Minnesota 4,283,880  New  York 385,477 

Alabama 2,041,793  New  Jersey 264,999 

Virginia... 859,466  Colorado 215,819 

Pennsylvania 747, 784  Georgia  and  N.  Carolina      175, 331 

Wisconsin „ 607.405  All  the  others 181,275 


Grand  total 16,005,449 

2.03.22.  NoTB.  Large  quantities  of  excellent  Bessemer 
hematite  are  shipped  to  Baltimore  and  other  Atlantic  ports 
from  the  mines  on  the  southeastern  coast  of  Cuba,  in  the  Jura- 
gua   Hills.     Santiago  de  Cuba  is  the  largest  town   in  this 


MAGNETITE  AND  PYRITE.  187 

region,  and  is  some  twenty  miles  west  of  the  mines.  The  coast 
range  of  hills  consists  mainly  of  syenite,  according  to  J.  P. 
Kimball,  and  the  syenite  is  penetrated  by  many  dikes  and  is 
mantled  by  sheets  of  diorite  with  which  the  ores  are  associated. 
Kimball  refers  the  precipitation  of  much  of  the  iron  oxide 
which  came  from  the  diorite  to  coraline  limestone,  which  had 
been  accumulated  as  coral  reefs  on  the  syenite  before  the 
diorite  was  intruded,  but  he  also  mentions  other  deposits  in 
the  diorite  not  associated  with  limestone.  From  observations 
of  another  group  of  ores  sixteen  miles  east  of  those  studied  by 
Kimball,  F.  F.  Chisholm  reached  a  different  conclusion  regard- 
ing their  origin.  Chisholm  refers  them  to  a  source  below  and 
apparently  regarded  them  as  veins  or  replacements  of  dikes. 
The  amount  of  ore  along  this  coast,  both  in  place  and  as  float 
is  very  great, ^  and  will  be  an  important  feeder,  to  American 
furnaces.  Between  three  and  four  hundred  thousand  tons  are 
now  annually  imported.  Chisholm  gives  the  following 
analyses : 

Fe.  S.  P. 

Juragua  (Kimball) 64.65  0 .146  0.037 

Sigua  (Graham) 64.00  0.040  0.016 

Berraco  (Chisholm) 60.00  0.027  0.027 

Although  not  a  source  of  supply  for  American  furnaces,  it  is 
interesting  to  note  in  this  connection  that  in  Mexico  vast  depos- 
its of  hematite  and  martite  occur  in  Cretaceous  limestone  asso- 
ciated with  intrusions  of  diorite.  The  paper  of  R.  T.  Hill 
cited  below  gives  a  review  and  full  bibliography  of  the  various 
localities.  The  notable  deposits  so  far  as  yet  opened  up  are  at 
the   Cerro  de  Mercado,  in  Durango,^  the  Sierra  de  Mercado, 

'  J.  P.  Kimball,  ' '  Geological  Relations  and  Genesis  of  the  Specular  Iron 
Ores  of  Santiago  de  Cuba,"  Amer.  Jour.  Sci.,  December,  1884,  p.  416;  also 
"The  Iron  Ore  Range  of  the  Santiago  District  of  Cuba,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XIII.,  613;  Eng.  and  Min.  Jour.,  December  20,  1884.  p. 
409.  F.  F.  Chisholm,  "Iron  Ore  Beds  in  the  Province  of  Santiago,  Cuba," 
Proe.  Colo.  Sci.  Soc,  III.,  259,  1890.  H.  Wedding,  "Die  Eisenerze  der 
Insel  Cuba,"  Stahl  und  Eisen.  1892,  No.  12.  Prof.  J.  W.  Spencer  has  been 
recently  working  on  the  geology  of  Cuba  and  presented  some  of  jiis  results 
at  the  meeting  of  the  American  Association  in  Brooklyn,  August,  1894. 

^  J.  Birkinbine,  "  The  Cerro  de  Mercado  or  Iron  Mountain  of  Durango," 
Trans.  Amer.  Inst.  Min.  Eng.,XUI.,  189,  1884.  J.  P.  Carson,  "Iron 
Manufacture  in  Mexico."  Idem.  VI.,  399.     R.  T.  Hill,  "The  Occurrence  of 


188  KEMP'S  ORE  DEPOSITS. 

near  Monclova  in  Coahuila/  and  others  of  minor  importance 
in  the  States  of  Jalisco/  Guerrero^  and  elsewhere.  Several  of 
these  are  now  the  basis  of  a  small  local  smelting  industry. 

Hematite  and  Martite  Iron  Ores  in  Mexico,"  Amer.  Jour.  Sci.,  February, 
1893,  111.  B.  Silliman,  "Martite  of  the  Cerro  de  Mercado,  or  Iron  Moun- 
tain of  Durango,  and  Certain  Iron  Ores  of  Sinaloa,"  Amer.  Jour.  Sci., 
November,  1882,  375.  See  also  on  the  Durango  Iron  Mountain,  Annales  del 
Ministerio  de  Fomento  de  la  Rep.  Mexicana  Tomo,  III. ,  1877 ;  Eng.  and 
Min.  Jour,  on  "Iron  in  Mexico, "  November  10,  1888,  p.  391. 

*  P.  Frazer,  "Certain  Silver  and  Iron  Mines  in  the  States  of  Nueva 
Leon  and  Coahuila,  Mex.,"  Trans.  Amer.  Inst.  Min.  Eng.,  XII.,  537.  R. 
T.  Hill,  as  cited  in  previous  footnote. 

'  J.  P.  Carson,  as  cited  in  second  footnote. 

'  N.  S.  Manross,  "Notes  on  Coal  and  Iron  Ores  in  State  of  Guerrero, 
Max.,  Amer.  Jour.  Sd.,  May,  1865,  p.  309;  Remarks  by  J.  D.  Dana,  p.  358. 


CHAPTER  IV. 


COPPER. 


2.04.01.     Copper  Ores. 


TABLE  OF  ANALYSES. 

Native  copper  (generally  with  some  silver) 

Chalcocite,  CU2S 

Chalcopyrite,  CuFeSj 

Bornite,  CugFeSg 

Tetrahedrite,  4CuS2,  Sb^S 3 (variable)  26.50  Sb. . 

Enargite,  Cug ASS4  (As,  19. 1) 

Cuprite,  CU2O 

Melaconite  (tenorite) ,  CuO 


Azurite,  SCuOCOg,  H^O 

Chrysocolla,  CuOSiOg,  2HgO. 


Cu. 
100.00 
79.80 
34.60 
61.79 
36.40 
48.40 
88. 8G 
79.86 
40.28 
46.31 
22.06 


20.2 
34.9 
25.8 
26.7 
32.5 


Fe. 


30.50 

11.70 

1.39 


2.04.02.  Example  16,  Continued.  Pyrite  or  pyrrhotite 
beds  (veins),  with  intermingled  chalcopyrite.  Whether  the 
deposits  are  true  beds  or  veins  parallel  with  the  foliation,  is  as 
yet  a  matter  of  dispute.  The  resemblance  to  magnetite  sug- 
gests a  bed,  and  this  view  is  generally  taken  by  German 
writers.  The  California  mines  occur  closely  associated  with 
the  auriferous  (pyritous)  quartz  bodies,  which  are  always 
esteemed  veins.  But  as  detailed  knowledge  increases,  it  is 
more  and  more  appreciated  that  the  ore  bodies  are  mostly  if 
not  entirely  veins  and  have  been  deposited  along  lines  of  dig- 
location.^ 

Pyrites  and  pyrrhotite  (called  mundic  by  the  miners)  are  the 
principal  constituents  of  such  bodies,  but  often  the  copper 
reaches  2.5  to  5%,  and  then  they  are  valuable  for  copper.  There 

*  Compare  in  this  connection  J.  H.  L.  Vogt.  "  Ueber  die  Kieslagerstat 
ten  von  Typus  Roros  Vigsnas,  Sulitelma  in  Norwegen  und  Rammelsberg 
in  Deutschland,"  Zeitschr.  fur  prakt.  Geologie.  February,  April  and  May, 

1894. 


190  KEMP'S  ORE  DEPOSITS. 

is  quite  a  characteristic  group  of  minerals  that  is  associated 
with  the  ores.  Zinc  blende  is  almost  always  present  in  small 
quantities,  and  is  a  great  drawback  to  the  ore  when  employed 
for  acid.  Galena  is  met  in  traces.  Quartz,  calcite,  some  form 
of  amphibole,  and  often  very  beautiful  garnets  are  associated. 
Ducktown  is  noted  for  its  zoisite.  All  the  secondary  minerals 
of  the  oxidized  zones  of  sulphides  are  met.  The  ores  are  often 
roasted  for  sulphurous  fumeS  in  acid  works,  and  afterward  the 
residues  are  shipped  to  the  copper  smelters.  The  mines  have 
been  or  are  being  worked  for  copper  near  Sherbrooke,  and  at  a 
great  number  of  other  points  in  Quebec,  just  north  of  Vermont. 
There  are  also  not  a  few  localities  in  Maine,  New  Brunswick, 
Nova  Scotia  and  Newfoundland,  where  operations  of  a  more  or 
less  serious  nature  have  been  undertaken.  Citations  to  the 
literature  regarding  these  will  be  found  at  the  close  of  the 
description  of  Ducktown.  At  Milan,  N.  H.,  there  are  several 
deposits  in  argillitic  schists,  and  in  the  same  region  there  are 
numerous  other  locations.  At  Vershire,  Vt.,  there  is  a  belt 
some  twenty  miles  long,  with  three  principal  mining  points. 
Of  these  the  middle  one,  containing  the  Ely  mine,  is  the 
largest.  Two  beds  of  ore  occur,  separated  by  from  10  to  20 
feet  of  schists.  The  lower  averages  about  four  feet,  but  fluc- 
tuates; the  upper  is  still  more  variable,  and  may  reach  25  feet. 
They  are  both  formed  by  a  succession  of  thin  lenses.  The  ore 
is  chalcopyrite,  mingled  with  pyrrhotite  and  quartz. 

2.04.03.  More  complete  observations  are  available  upon  the 
Ducktown,  Tenn.,  deposits,  than  upon  any  others  of  the  type  in 
America.  The  excellent  paper  by  Carl  Henrich  is  here  spe- 
cially drawn  upon  and  has  been  supplemented  b3'  some  few  fur- 
ther notes  by  the  writer.  Ducktown  is  situated  in  the  south- 
eastern township  of  Tennessee,  and  occupies  a  small  plateau 
between  bounding  ranges  of  higher  mountains.  The  plateau 
has  been  much  dissected  by  the  present  drainage,  but  its  stumps 
remain,  and  serve  to  indicate  the  peneplain  of  Tertiary  date.^ 
The  country  rock  is  mica  schist,  with  occasional  heavier  beds 
that  tend  toward  quartzite  or  even  gneiss.  Some  horn  blend  ic 
rocks  are  present  with  the  ores,  but  whether  they  represent  in- 
truded dikes  as  suggested  by  Henrich,  or  streaks  of  siliceous 

*  C.  W.  Hayes,  '' Geomorphology  of  the  Southern  Appalachians,"  Na- 
tional Geographic  Magazine,  VI.,  68,  1894. 


^ig.  2. 


yOutCTops  of 
Scale  li"-  1  Mile 


MAP  Of  THE  DUCKTOW.N.  MINES. 

FiQ.55.—Map  of  the  mines  and  of  the  outcrop  of  gossan,  showing  the  relations 

and  extent  of  the  veins  at  Ducktown,  Tenn.     After  Carl  Henrich, 

Trans.  Amer.  Inst.  Min.  Eng.,  XXV.,  178,  1895. 


192  KEMP'S  ORE  DEPOSITS. 

limestone,  it  is  not  possible  to  determine.  The  schists  are 
metamorphosed  shales,  and  the  schistosity  appears  to  be  gener- 
ally parallel  to  the  original  bedding.  The  geological  age  is 
still  in  dispute,  but  is  probably  Pre-Cambrian. 

The  schists  strike  N.  20-25  E.,  and  have  a  prevailing  dip  of 
about  50  to  55  S.  E.  There  are  variations  of  the  latter  which 
are  due  to  rolls  and  faults.  The  schists  have  been  broken  by 
dislocations  along  which  the  ores  have  been  deposited.  The 
strike  of  the  ore  is  parallel  to  the  strike  of  the  schists,  and  the 
dip  is,  as  a  rule,  the  same  as  that  of  the  schists,  but  cases  have 
been  observed  where  the  ores  cut  the  dip  of  the  country  rock,  al- 
though with  such  soft  and  easily  mashed  materials  it  is  diffi- 
cult to  identify  the  unconformity.  There  are  two  principal 
belts  of  fracture  as  shown  by  the  map,  Fig.  55,  and  probably 
several  minor  ones,  between.  The  Old  Tennessee,  Burra  Burra, 
London  and  East  Tennessee  lie  along  the  northwest  belt;  the 
Polk  County,  Mary,  and  Calloway  form  the  southeast  belt ; 
and  the  Culchote  and  Isabella  lie  in  the  interval.  The  ore 
bodies  are  huge  lenticular  masses  of  sulphides,  which  probably 
owe  this  shape,  as  far  as  it  is  at  all  discernible,  to  diagonal 
faulting  since  the  veins  were  filled.  The  common  ore  is  an 
aggregate  of  pyrrhotite,  chalcopyrite,  calcite,  quartz,  zoisite, 
and  in  some  mines  much  actinolite.  Zinc  blende  and  galena 
are  present,  but  are  insignificant.  Garnets  are  occasionally  met 
in  quantity.  On  some  of  the  claims  pyrites  is  abundant,  as  in 
the  Burra  Burra,  and,  as  is  reported  to  be  the  case  at  the  Isa- 
bella, it  taking  the  place  of  the  pyrrhotite  to  a  greater  or  less 
degree.  The  content  of  copper  varies  up  to  3.5%,  with 
occasional  bunches  that  run  higher.  The  old  black  copper  ores 
that  accumulated  at  the  water-level  are  now  exhausted.  (See 
Fig.  56.)  From  observations  on  the  succession  and  character  of 
the  minerals  in  the  vein,  J.  F.  Kemp  has  drawn  the  following 
conclusions  regarding  the  geological  history  of  the  veins.  By 
a  process  of  regional  metamorphism,  a  sedimentary  series  of 
shales  and  sandstones  w^as  altered  to  mica  schists  and  quartz 
schists.  Where  the  ore  is  now  found,  zoisite,  tremolite,  and 
garnet  were  also  produced,  but  it  is  not  known  whether  they 
are  met  outside  of  the  mines  or  not.  They  indicate  the  former 
presence  of  magnesian  and  calcareous  rocks,  althougn,  gener- 
ally speaking,  lime  is  practically  unknown  in  the  metamorphic 


COPPER. 


193 


rocks  of  the  district  and  the  local  waters  are  remarkably  pure 
and  soft.  Whether  a  calcareous  shale  or  an  intruded  dike 
yielded  the  lime  silicates,  or  whether  they  are  metamorphosed, 
calcareous,  vein  material  from  an  older  vein  filling  cannot  be 
stated.  After  the  general  metamorphism,  a  series  of  disloca- 
tions was  developed  along  the  lines  of  the  present  veins,  and 


Cross-Section  A-A.  (Fig.  8.) 
Shaft  3.  Old  Tennessee  NIine^ 


Fig.  56. — Cross-section,  Shaft  3,  Old  Tennessee  Mine,  Ducktovm,  Tenn.,  show- 
ing the  gossan,  the  black  ore,  the  pyrrhotite  and  a  fault.     After  Carl 
Henrich,  Trans.  Amer.  Inst.  Min.  Kng.,  XXV.,  198,  1895. 

pyrrhotite  and  sometimes  pyrite  were  introduced.  After  the 
deposition  of  the  pyrrhotite  there  was  further  movement  which 
shattered  the  pyrrhotite  and  allowed  the  introduction  of  chal- 
copyrite  in  streaks  and  fine  veinlets  all  through  it.  Still  later, 
and  apparently  after  another  movement  calcite  came  in  and 


194  KEMP'S  ORE  DEPOSITS. 

penetrated  the  shattered  sulphides  and  older  silicates.  After  the 
introduction  of  the  calcite,  by  some  movement  fissures  notably 
horizontal  were  produced,  which  became  filled  with  glassy 
quartz,  and  which  have  yielded  the  so-called  **fioors."  More 
or  less  contemporaneously  with  the  quartz,  coarsely  crystalline 
pyrrhotite,  chalcopyrite  and  blende  were  produced,  which  are 
in  marked  contrast  with  the  earlier  sulphides.  The  oxidation 
of  the  veins  above  the  ground  water,  the  formation  of  the 
brown  hematite  outcrops  and  the  development  of  the  zone  of 
enrichment  (the  black  ores)  bring  the  process  down  to  the 
present.^ 

2.04.03.  Throughout  the  mountainous  region  of  western 
North  Carolina,  eastern  Tennessee  and  northern  Alabama  are 
many  other  copper  deposits  of  rbore  or  less  serious  importance. 
One  of  the  best  known  is  the  one  formerly  operated  at  Ore 
Knob. 

This  is  described  by  Kerr  as  a  true  fissure  vein,  extending 
2,000  feet  on  the  strike,  which  is  parallel  to  that  of  the  gneiss, 
but  cutting  the  dip  in  descent.  The  width  averaged  about  10 
feet.  The  gossan  extended  to  a  depth  of  50  feet,  and  furnished 
the  usual  body  of  rich  ore  at  the  contact  with  the  sulphides. 
The  mine  has  not  been  operated  for  some  years.^ 

^  Trans.  Amer.  Inst.  Min.  Eng.,  1899. 

"  For  a  general  account  of  the  sulphides  in  the  East,  see  A.  Wendt,  "The 
Pyrites  Deposits  of  the  Alleghanies,"  School  of  Mines  Quarterly,  VII.,  1886. 

Canada,  Geol.  Survey  of  Canada,  1863,  709.  James  Richardson,  Idem,, 
1896,  34-44.  R.  W.  Ells,  "Copper  in  Quebec,"  Idem,  1890,  Vol  IV., 
29K.  Rec.  "The  Mining  Industries  of  Eastern  Quebec,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XVIII. ,  316,  1889.  John  Blue,  "  Copper  Pyrites  Min- 
ing in  Quebec  in  1894,"  Journal  Gen  I  Mining  Assoc.  Prov.  Quebec,  II., 
147,  1894.  S.  L.  Spofford,  "  Albert  Mines  and  Capelton  Chemical  Works, " 
Idem,  214.  C.  T.  Jackson,  "The  Great  Copper-bearing  Belt  of  Canada," 
Proc.  Bost.  SoG.  Nat.  Hist.,  IX.,  202,  1862.  Copper  prospects  have  received 
attention  in  southwestern  New  Brunswick,  on  Adams,  Campobello,  and 
other  islands.  See  Bailey  and  Matthew,  Geol.  of  Canada,  1870-71,  p.  13. 
"  On  Notre  Dame  Bay,  Newfoundland, "  M.  E  Wadsworth,  Amer.  Jour. 
Sci.,  in. ,  XXVIII. ,  28,  102. 

Maine. — "Blue  Hill  District",  E7ig.  and  Min.  Jour.,  August  28,  1880,  p. 
140.  F.  L.  Bartlett,  "Mines  of  Maine,"  in  Mines,  Miners  and  Mining 
Interests  of  the  United  States,  Philadelphia,  1882,  133.  J.  D.  Whitney, 
Metallic  Wealth  of  the  United  States,  312. 

New  Hampshire.— C.  H.  Hitchcock,  Geol.  of  N.  H.,  III.,  Part  III,,  p  47. 

Vermont. — "Elizabeth  Copper  Mines,"  E7ig.  and  Min.  Jour.,  November 


I 


COPPER.  195 

2.04.04.  Example  166.  Spenceville,  Cal.  Copper  ores 
are  known  and  have  been  more  or  less  worked  in  a  number  of 
places  along  the  western  Sierras,  of  which  Spenceville,  Nevada 

6,  1886,  p.  337;  ''The  Pyrrhotite  of  the  Ely  Mine,"  Idem,  April,  10,  1886, 
263.  F.  M.  F.  Cazin,  Trans.  Amer.  Inst.  Min.  Eng.,  XXIII.,  604,  1894.  H. 
Koehnike,  "Die  Vermont  Kupf er-Grube, "  Berg-  u.  HiXtten.  Zcit.,  1892, 
297.  Richardson,  "Copper  Ore  of  Stafford,  Vt.,"  Amer.  Jour.  Sci.,  i., 
XXI.,  383.  H.  S.  Wheeler,  "  Copper  Deposits  of  Vermont," -Sc/iooZ  o/ 
Mines  Quarterly,  IV.,  219.     Rec. 

Pennsylvania.— Maryland,  and  Virginia.— J.  F.  Bailey,  "Copper 
Deposits  of  Adams  County,  Pa.,"  Eng.  and  Min.  Jour.,  February  17, 1883, 
88.  J.  F.  Blandy,  "Lake  Superior  Copper  Rocks  in  Pennsylvania," 
frans.  Amer.  Inst.  Min.  Eng.,  VII.,  331.  P.  Frazer,  "Some  Copper  De- 
posits of  Carroll  County,  Md.,"  Trans.  Amer.  Inst.  Mm.  Eng.,  IX.,  23. 
1881.  "Hypothesis  of  the  Structure  of  the  Copper  Belt  of  the  South 
Mountain,  Idem,  XII. ,  82, 1884.  ' '  Geology  and  Copper  Deposits  of  Adams 
County,  Pa.,"  Eng.  and  Min.  Jour.,  XXXV.,  112,  1883.  C.  H.  Hender- 
son, "Copper  Deposits  of  the  South  Mountain,  Pa.,"  Trans.  Amer.  List. 
Min.  Eng.,  XII.,  85,  1884.  C.  T.  Jackson,  "Copper  Mine,  Elk  Run, 
Fauquier  County,  Va.,"  Proc.  Bost.  Soc.  Nat.  Hist,  VI.,  183,  1857. 
Arthur  Keith ,  Harper's  Ferry  Folio,   U.  S.  Geological  Survey. 

North  Carolina,  Tennessee,  and  Alabama.—"  The  Stone  Hill  Cop- 
per Mine  and  Works,  Cleburne,  Ala,.,"  Eng.  and  Min.  Jour.,  August  4, 
11,  18,  1877,  pp.  86  and  following.     W.  P.  Blake,  "  Notes  and  Recollections 
Concerning  the  Mineral  Resources  of  Northern  Georgia  and   Western 
North  Carohna,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXV.,  796.   W.  B.  Brewer 
"Ducktown  Copper  Mining  District,"  £^ngr.  and  Min.  Jour.,  March  23^ 
1895,  271.     "Copper  Mining  in  Alabama,"  Proc.  Ala.  Ind.  and  Sci.  Soc, 
VII.,  13,  1897.     Carl  Henrich,  "The  Ducktown  Deposits  and  the  Treat 
ment  of  the  Ducktown  Copper  Ores,"  Trans.  Amer.   hist.  Min.   Eng 
XXV.,  173,    1895.     Rec.     J.  F,  Kemp,    'The  Order  of  Formation  of  the 
Minerals  in  the  Ducktown  Veins,"  Idem,  1899.     T.  S.  Hunt,  "Ore  Knob 
and  Some  Related  Deposits,"  Trans.  Amer.  Inst.    Min.   Eng.,  II.,  125. 
Kleinschmidt  (on  Virginia,  Tennessee,  and  North  Carolina),  Gangstudien, 
Vol.  III.,  p.  256.     (A  good,  short,  but  old  account.)     E.  E.  Olcott,  "Ore 
Knob  Copper  Mine  and  Reduction  Works,  '  Trans.  Amer.  Inst.  Min.  Eng., 
HI.,  391.     Rec.     W.  B.  Phillips.   "Copper  Deposits  of  North  Carolina," 
Eng.  and  Min.  Jour.,  April  1,  1899,  382.     Tripple  and  Credner,   "Report 
on  the  Ducktown  Region  to  the  American  Bureau  of  Mines,"  1866.     M. 
Tuomey,  '  'A  Brief  Note  of  Some  Facts  Connected  with  the  Ducktown 
(Tenn.)  Copper  Mines,"  Amer.  Jour.  Sci..,  II.,  19,  181.     A.  F.  Wendt, 
"  The  Pyrites  Deposits  of  the  Alleghanies, "  School  of  Mines  Quarterly,  Vol. 
VII.,  1886;  Eng.  and  Min.  Jour.,   July   10  and  following,  1886.     J.  D. 
Whitney,  "Remarks  on  the  Changes  that  Take  Place  in  the  Structure  and 
Composition  of  Mineral  Veins,"  etc.,  with  especial  reference  to  Ducktown, 
Tenn.,   Amer.  Jour.  Sci.,  ii.,  XX.,  53. 


196  KEMP'S  ORE  DEPOSITS. 

County,  Copperopolis  and  Campo  Seco,  Calaveras  County,  and 
Newton,  Amador  County,  are  the  most  important.  There  are 
some  differences  m  the  geological  relations  of  these  several 
deposits,  but  they  are  alike  in  being  associated  with  igneous 
rocks.  At  Spenceville  the  ores  occur  in  veins  along  the  contact 
of  diabase  and  grano-diorite.^  In  Amador  County  two  belts 
of  ore  have  been  developed  in  amphibole  schists.  There  are 
mines  at  lone  and  Caledonia,  and  other  openings  extend  in  a 
southeasterly  line  to  Copperopolis  in  Calaveras  County.  The 
amphibolite  schist  is  a  metamorphosed  diabase  or  porphyrite. 
In  some  of  the  mines  quartz  porphyrite  is  associated  with  the 
veins.^  Other  copper  deposits  have  been  discovered  in  the  areas 
covered  by  the  Sonora  and  Placerville  folios.^  They  occur  in 
porphyrites,  amphibole-schists,  serpentine,  and  in  contact  zones 
next  the  intrusions  of  grano-diorite. 

Far  to  the  north  of  all  the  deposits  cited  above  a  very  extensive 
body  of  sulphides  has  been  opened  at  Iron  Mountain,  and  bids 
fair  to  afford  high-grade  ore  for  this  type.  The  wall  rock  is 
described  as  a  highly  siliceous  porphyry.* 

The  California  copper  ores  have  been  treated  by  wet  methods 
to  a  large  extent,  and  have  contributed  considerable  amounts 
to  the  total  output  of  the  country. 

Note.  For  Example  16c,  see  under  Nickel.  Some  of  the 
California  mines  appear  to  be  closely  related  to  16c. 

2.04.05.  Example  17.  Butte,  Mont.  Veins  in  fissures  in 
granite,  which  have  involved  but  slight  dislocation,  and  which 
have  been  enlarged  by  replacement  of  the  walls  with  ore.  The 
vein  filling  is  siliceous,  and  the  metallic  ores  in  the  deposits 

'  Lindgren  and  Turner,  Smartsville  Folio,  U.  S.  Geological  Survey. 
See  also  J.  E.  Ellis,  "On  the  Spenceville  Mines,"  Mineral  Resources  of 
the  U.  S.;  U.  S.  Geol.  Survey,  1884,  340.  H.  G.  Hanks,  Rept.  of  California 
State  Mineralogist,  1884,  151.     J.  B.  Hobson,  Idem,  for  1890,  392. 

■^  H.  W.  Turner,  Jackson  Folio,  U.  S.  Geol.  Survey.  H.  G.  Hanks, 
"  On  Calaveras  County  Mines,"  Fourth  Ann.  Rep.  Cal.  State  Mineralogist, 
48,  1890.  Wm.  Irelan,  Idem,  1888,  150-153;  "On  the  Newton  Mines, 
Amador  Co.,"  Idem.,  p.  106. 

^  Turner  and  Ransome,  Sonora  Folio ;  Lindgren  and  Turner,  Placerville 
Folio,  U.  S.  Geol.  Survey. 

*  H.  Lang,  "Iron  Mountain  Mine,  Shasta  Co.,"  Eng.  and  Min.  Jour., 
April  15,  22,  and  May  13,  1899.  The  paper  also  mentions  other  copper 
mines  in  this  region. 


COPPER.  197 

productive  of  copper  are  chalcopyrite,  pyrite,  boroite,  chalco- 
cite,  enargite,  aud  rarely  covellite  and  tennantite.  The  copper 
ores  contain  much  silver  and  some  gold,  but  there  is  a  fairly 
distinct  series  of  silver-bearing  veins,  which  contain  practically 
no  copper,  and  which  have  manganese  minerals  that  fail  in  the 
copper  veins.  And  yet  along  the  borders  of  the  two  areas 
there  are  veins  which  are  somewhat  transitional  between  the 
two  varieties. 

The  geological  formations  at  Butte  are  illustrated  on  the 
accompanying  map,  Figs.  58  and  59,  which  are  based  upon  the 
map  of  the  areal  geology  in  the  Butte  Special  Folio  of  the  U,  S. 
Geological  Survey.  The  colors  of  the  original  are  reproduced 
in  lines,  and  some  small  details  have  necessarily  been  omitted 
on  account  of  the  reduction  in  size,  and  the  confusion  of  signs 
without  colors.  The  only  omissions,  however,  are  a  few  small 
areas  of  the  Bluebird  granite,  and  of  the  rhyolite.  In  the 
orginal  map  the  areal  geology  is  by  W.  H.  Weed,  and  the  veins 
and  mining  geology  have  been  mapped  by  S.  F.  Emmons  and 
G.  W.  Tower.  The  work  was  difficult  and  complicated,  but  it 
has  been  admirably  done. 

The  Butte  mining  district  lies  on  the  southern  and  eastern 
slopes  of  a  hillside  or  upland  that  rises  from  the  vallej'  of  Sil- 
ver Bow  Creek.  The  hillside  is  cut  by  several  minor  north  and 
south  gulches,  and  is  bounded  on  the  south  and  east  by  the 
valley  of  the  creek,  which  makes  a  crescentic  sweep  around  it. 
Just  to  the  west  of  the  town  rises  a  sharp  cone  of  rhj'-olite, 
which  is  shown  in  Fig.  60,  and  which  gave  the  camp  its  name 
in  the  early  days.  In  the  distance,  on  all  sides,  high  mountain- 
ous ridges  rise  like  walls  as  is  shown  in  Figs.  61  and  62.  The 
oldest  rock  of  the  district,  and  the  one  which  covers  the  greatest 
area,  is  a  basic  granite.  Chemical  analyses  prepared  by  the  U. 
S.  Geological  Survey  have  proved  it  to  be  exceptionally  low  in 
silica  for  a  granite,  and  to  be  quite  uniform.  SiO^  63.88-64.34, 
AI2O3,  15.38-15.84,  FeO,  Fe203,  4.5-4.7,  CaO,  3.97-4.3,  MgO, 
2.08-2.23,  K2O,  4.0-4.23,  Na20,  2.74-2.81.  This  rock  is  called 
the  Butte  granite.  It  is  the  wall-rock  of  all  the  copper  veins 
and  of  most  of  the  silver  ores.  It  lies  east,  north  and  south  of 
the  Big  Butte.  The  intrusion  of  the  Butte  granite  was  followed, 
presumably  after  a  short  interval,  by  a  white,  acidic  granite 
known  as  the  Bluebird.     An  interesting  contact  of  the  two  is 


198 


KEMP'S  ORE  DEPOSITS. 


BUTTE  GRANITE  BLUEBIRD  GRANITE  QUARTZ  PORPHYRY  RHYOLITE 


^^ 


Fig,  58. — Geological  map  of  the  Western  half  of  Butte  District,  Montana,  re- 
produced in  line-work  from  the  colored  map  of  the  Butte  Special 
Folio,  U.  S.  Geological  Survey. 


COPPER. 


19!) 


LAKE  BEDS 


M^.UVIUM  CnpPEK  VEINS  SILVER  VEINS         CoW^MZvek 


Fig.  m.— Geological  map,  Kastern  half,  Butte  District,  Montana, 
See  Fig.  58. 


200  KEMP'S  ORE  DEPOSITS. 

shown  ID  Fig.  63.  It  is  supposed  to  have  separated  from  the 
same  magma  that  afforded  the  Butte  granite  and  to  have  pene- 
trated fissures  in  the  latter  while  it  was  probably  still  hot,  as  it 
is  now  found  in  all  manner  of  small  veins  and  masses,  which  do 
not  show  any  effects  of  quick  chilling  along  the  contacts.  The 
Bluebird  granite  is  most  extensively  developed  in  the  western 
part  of  the  district,  but  it  appears  on  all  sides  of  the  Big  Butte 
in  small  patches.  The  next  rock  in  time  is  quartz-porphyry, 
which  is  found  on  the  slopes  west  of  Butte  City,  and  between  it 
and  Meaderville.  After  the  intrusion  of  the  quartz-porphyry  the 
fracturing  occurred,  which  gave  rise  to  the  veins,  for  the  latter 
cut  the  quartz-porphyry  in  a  number  of  instances.  After  the 
deposition  of  the  ore,  the  great  intrusion  and  eruption  of  the 
rhyolite  took  place,  which  now  appears  as  many  dikes  cutting 
the  veins,  as  a  great  sheet,  and  as  some  masses  of  fragmental 
ejectments.  While  the  rhyolite  was  in  eruption  a  lake  existed 
in  the  western  part  of  the  district,  and  in  it  were  deposited 
great  quantities  of  rhyolitic  volcanic  dust,  which  now  chiefly 
constitutes  the  Lake  Beds  of  the  map.  These  beds  have  been 
traced  to  the  south  and  west  beyond  the  limits  of  the  map,  and 
have  been  found  to  contain  Miocene  fossils. 

Outside  the  area  of  the  map  the  Butte  granite  is  known  to 
penetrate  Carboniferous  strata,  and  it  is  not  certain  that  it  may 
not  have  followed  Laramie  beds.  It  is,  certainly  post-Carboni- 
ferous, and  it  may  be  post-Laramie.  The  veins  must,  there- 
fore, have  been  filled  in  the  interval  between  the  close  of 
the  Carboiliferous  and  the  Miocene,  and  perhaps  are  post-Cre- 
taceous. The  recent  gravels  constitute  the  formation  called 
alluvium.  They  are  extensive  in  the  valleys  of  the  creeks  and 
at  times  quite  deep. 

Butte  was  first  developed  as  a  placer  camp  as  early  as  1864, 
when,  according  to  Emmons  and  Tower,  the  gravels  of  Mis- 
soula Gulch  were  washed.  As  the  quartz  ledges  constituting 
the  veins  still  project  in  many  instances,  like  great  walls,  it  is 
not  surprising  that  they  were  early  noted  and  located.  Figures 
illustrative  of  them  and  of  the  excessive  weathering  of  the  Butte 
granite  will  be  found  under  silver  in  Montana,  Chapter  X.  Small 
success  attended  the  first  efforts  of  the  deep  miners  until  rich 
silver  ore  was  found  in  the  Travona  in  1876.  The  copper  dis- 
coveries came  three  or  four  years  later,  because  the  copper  had 


Fig.  60. — View  of  the  Big  Butte,  Butte  City,   Mont.,  looking  northwest 

across  Missoula  Gulch.    From  a  photograph  by 

J.  F.  Kemp,  June,  1896. 


Fig.  Ql.—View  of  the  Anaconda  Mine  {with  the  nine  stacks),  Butte,  Mont, 
From  a  photograph  by  Alexander  Brown,  E.  M.,  1896. 


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COPPER.  201 

been  leached  out  of  the  portion  of  the  vein  above  the  ground- 
water, leaving  the  silver  behind.  When,  however,  the  huge 
masses  of  chalcolite  and  bornite  were  met  in  the  zone  of 
enrichment,  the  copper  production  became  established. 

Study  of  the  map  will  show  that,  although  so  numerous,  the 
veins  all  run  in  an  east  and  west  direction,  that  they  are  closely 
parallel,  and  that  at  the  most  they  vary  not  more  than  45  degrees 
north  or  south  of  this  line.  They  dip  at  high  angles,  being 
almost  always  over  60  degrees.  The  dip  is  to  the  south,  except 
in  the  northern  edge  of  the  district,  where  the  inclination  is 
prevailingly  to  the  north. 

Small  offsetting  veins  often  connect  the  larger  ones  and  even 
run  into  the  wall  rock  as  blind  veins.  Veinlets  of  all  sizes  can 
be  observed  on  the  dumps.  The  ore  varies  from  live  or  six  feet 
to  as  much  as  100  feet  across  in  the  extreme  cases.  The  origi- 
nal fissures  do  not  appear  to  have  involved  much  empty  space, 
however,  and  the  deposition  has  been  in  the  nature  of  a  replace- 
ment of  the  walls,  and  the  process  may,  indeed,  have  extended 
from  fissure  to  fissure,  removing  the  intervening,  rarely  brec- 
ciated  country  rock.  The  ore  habitually  fades  out  into  the  coun- 
try rock  at  least  on  one  side,  and  as  a  rule  all  the  companies 
have  to  concentrate  the  run  of  the  mines.  Since  the  completion  of 
ore  deposition,  there  has  been  extensive  later  dislocation,  which 
is  shown  by  brecciated  faults,  which  maj^  follow  along  the 
veins,  or  may  cross  and  fault  them.  They  are  now  filled  with 
material  more  or  less  fully  kaolinized  and  are  practically  bar- 
ren, except  where  they  have  dragged  vein  matter  into  their 
substance  during  faulting,  or  have  been  impregnated  during 
the  alteration  of  the  older  veins. 

2.04.06.  The  ground  distinctively  productive  of  copper  is 
quite  sharply  marked  off  from  that  yielding  silver  alone  (all 
the  copper  ores  have  silver)  and  a  wavy  line  has  been  run 
around  the  former  on  the  map.  The  copper  area  seems  to  have 
been  the  center  of  the  mineralization,  and  in  it  the  largest  ore- 
bodies  are  found.  Copper  and  silver  solutions  especially  fav- 
ored this  portion,  and  on  its  edges  the  copper  gradually 
failed,  while  with  the  silver  came  more  or  less  zinc  and  lead, 
and  increasing  manganese.  The  Gagnon  mine  that  is  on  the 
border  is  transitional,  as  the  ore  yields  copper,  but  is  also  very 
rich  in  silver,  and  contains  considerable  blende  and  galena. 


202  KEMP'S  ORE  DEPOSITS. 

The  miDeralogy  of  the  silver  series  is  more  fully  described 
under  Silver,  Chapter  X.  The  copper  ores  contain  a  small  but 
constant  value  in  gold,  and  there  is  some  reason  for  thinking 
that  the  gold  occurs  as  a  telluride.  While  tellurium  is  present 
in  very  small  amounts,  it  can  be  saved  by  the  refiners  and  sup- 
plied in  quantities  that  are,  for  this  rare  element,  enormous. 

The  oxidizatiah  or  alteration  of  the  veins  above  the  ground- 
water presentsloints  of  interest.  As  the  v^^all-rock  is  granite, 
carbonates  and  oxides  of  copper  are  poorly  developed  and  the 
oxidized  ores  are  in  contrast  with  those  in  limestones  and 
schists.  Chalcocite,  bornite  and  covellite  are  the  principal 
secondary  copper  minerals  that  have  resulted,  and  the  last  named 
lies  chiefly  along  fractures.  The  chalcocite  and  bornite  are  not, 
however,  limited  to  the  present  water-level,  but  have  pene- 
trated far  below  it,  and  have  enriched  the  veins,  and  a  reasona- 
ble query  may  be  raised  as  to  whether  they  may  not  be  in  part 
original  depositions.  The  gangue  is  quartz,  in  decomposed 
country  rock.  Barite  in  honey-yellow  tabular  crystals  is  oc- 
casionally met,  but  is  only  a  curiosity.  The  outcrop  of  the 
silver  veins  is  stained  black  by  manganese  oxide. 

To  the  east  of  the  area  of  the  map  and  on  the  slopes  of  the 
bounding  range  of  granite  mountains,  the  veins  outcrop  as 
ledges  of  quartz,  and  considerable  prospecting  has  been  done. 
Some  copper  ores  have  indeed  been  found,  but  the  developments 
do  not  yet  (1899)  assure  profitable  mining. 

2.04.07.  The  total  production  of  Butte  to  the  close  of  1896 
is  estimated  by  Emmons  and  Tower  to  have  been  1300,000,000, 
divided  somewhat  as  follows:  Gold,  500,000  ounces;  silver, 
100,000,000  ounces;  copper,  1,000,000,000  pounds.  In  1897, 
according  to  The  Mineral  Industry,  the  copper  produced  was 
237,158,540  pounds,  of  which  the  Anaconda  Company  con- 
tributed 131,471,127.  On  the  whole,  the  Butte  copper  district 
is  the  most  productive  of  those  as  yet  opened  in  the  United  States.^ 

^  The  best  account  of  Butte  will  be  found  in  the  Butte  Special  Folio,  of 
the  U.  S.  Geol.  Survey,  in  which  the  areal  geology  is  by  W.  H.  Weed,  and 
the  mining  geology  by  S.  F.  Emmons  and  G.  W.  Tower.  This  reference 
has  been  especially  drawn  upon  in  the  above  description.  ' '  Butte  Copper 
Mines,"  Eng.  and.  Min.  Jour.,  April  24,  1886,  299;  June  19,  1886,  445.  R. 
G.  Brown,  "The  Ore  Deposits  of  Butte  City,"  Trans.  Amer.  Inst.  Min. 
Eng.,  XXIV.,  543.  Rec.  S.  F.  Emmons,  "Notes  on  the  Geology  of 
Butte,  Mont.,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  49.     Ch.  W.  Goodale, 


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V 


COPPER.  203 

There  are  copper  prospects  in  northwestern  Montana  within 
the  limits  of  the  Lewis  and  Clarke  Timber  Reserve,  and  amid 
the  high  peaks  of  the  Rockies  near  the  international  boundary. 
The  general  geology  ,^  the  country  involves  Cambrian  and 
Precambrian  quartzites,  in  which  are  intrusions  of  igneous 
rocks,  of  the  nature  of  andesites  or  diorites.  Copper  ores  are 
found  in  association  with  the  latter/ 

2.04.08.  Example  17a.  Gilpin  County,  Colorado.  Veins  of 
pyrite  and  chalcopyrite,  replacing  gneiss  (the  rock  may  be 
granite),  and  dikes  of  quartz- porphyry,  and  felsite  along  the 
planes  of  joints,  which  cross  the  gneiss  (or  granite)  perpendic- 
ularly to  the  laminations.  The  veins  are  highly  auriferous, 
and  are  worked  primarily  for  gold,  the  copper  being  produced 
as  a  by-product.  The  concentrates  from  the  stamps  are  after- 
ward treated  for  copper.  The  veins  occupy  an  area  of  only 
about  a  mile  and  a  half  in  diameter,  centering  about  Central 
City.  They  show  little  indication  of  having  filled  a  fissure,  as 
usually  understood,  but  follow  the  cleavage  joints  of  the  gneiss, 
and  replace  the  countr}"  rock  on  each  side  of  them.  The  joints 
also  cross  the  porphyry  dikes,  and  the  veins  are  often  in  the 
latter  rock.  They  are  closely  related  in  structure*  and  origin 
to  the  galena  veins  of  the  neighboring  Clear  Creek  County, 
which  are  referred  to  under  "Silver,*'  but  the  contrast  in  min- 
eral contents  between  the  two  is  very  marked.     They  were  the 

"The  Concentration  of  Ores  in  the  Butte  District,  Mont.,  Idem.,  XXVI., 
599,  1108.  Richard  Pearce,  "The  Association  of  Minerals  in  the  Gagnon 
Vein,  Butte  City,  Mont. ,  Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  63;  "On  the 
Occurrence  of  Goslarite  in  the  Gagnon  Mine,  Butte  City,  '"  Proc.  Colo. 
Set.  Soc,  Vol.  II.,  Part  I.,  p.  12.  E.  D.  Peters,  Mineral  Resources  of  the 
U.  S.,  1883-84,  p.  374.  A.  Williams  and  E.  D.  Peters,  "On  Butte,  Mont.," 
Eng.  and  Min.  Jour.,  March  23,  1885,  p.  208.  G.  vom  Rath,  "Ueber  das 
Gangrevier  von  Butte,  Mont.,"  Neues  Jahrbuch,  1885,  L,  158. 

Important  annual  reviews  are  also  published  in  the  Ann.  Reps,  of  the 
Director  of  the  U.  S.  Geol.  Survey  and  in  The  Mineral  Industry.  The  lat- 
ter is  especially  valuable  in  connection  with  the  technology  and  mining. 
Geneml  papers  on  copper  production  likewise  touch  on  Butte,  such  as 
James  Douglass,  "The  Copper  Resources  of  the  United  States,"  Trans. 
Amer.  Inst.  Min.  Eng.,  XIX.,  678.  Some  additional  literature  is  given 
under  "Silver,"  2.10.09. 

*^  R.  C.  Chapman,  "The  Geological  Structure  of  the  Rocky  Mountains, 
within  the  Lewis  and  Clarke  Timber  Reserve,"  Trans.  Amer.  Inst.  Min. 
Eng.,  February,  1899. 


204 


KEMP'S  ORE  DEPOSITS. 


basis  of  the  first  extensive  deep  mining  in  Colorado,  and  were 
located  through  the  placer  deposits  in  the  neighboring  gulches/ 

2.04.09.  Example  176.  Llano  County,  Texas.  Impregna- 
tions in  granite,  and  veins  with  quartz  gangue  in  granite,  carry- 
ing carbonates  above,  but  sulphurets  and  tetrahedrite  with  some 
gold  and  silver  below.  Contact  depo^it^  between  slates  and 
granite  are  also  known.  It  is  not  demonltrated  as  yet  whether 
the  ores  are  to  be  actually  productive.^ 

2.04.10.  Example  18.  Keweenaw  Point,  Michigan.  Native 
copper,  with  some  silver,  in  both  sedimentary  and  interstrati- 


FlG.  64. — Cross  section  of  the  Boh-tail  mines,  Central  City,  Colo. 
F.  M.  Endlich,  Hayden's  Survey,  1873,  'p.  286. 


After 


fied  igneous  rocks  of  the  Keweenawan  system.  The  metal  oc- 
curs as  a  cement  binding  together  and  replacing  the  pebbles  of 
a  conglomerate ;  or  filling  the  amygdules  in  the  upper  por- 
tions of  the  interbedded  sheets  of  massive  rocks;  or  as  irregular 
masses,  sometimes  of  enormous  size,  in  veins,  with  a  gangue 
of  calcite,  epidote,  and  various  zeolites ;  or  in  irregular  masses 
along  the  contacts  between  the  sedimentary  and  igneous  rocks. 
(For  the  general  geography  see  Fig.  24,  p.  126.) 
2.04.11.     The    rocks  of  the  Keweenawan   system  are  most 

^  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII. ,  p.  68.  The  veins  are  de- 
scribed as  cited  above.  J.  D.  Hague,  Fortieth  Parallel  Survey,  III. ,  p.  493. 
The  veins  are  called  fissure  veins  by  Mr.  Hague.  A.  Lakes,  Ann.  Rep. 
Colo.  State  School  of  Mines,  1887,  p.  103.  A.  W.  Rogers,  "The  Mines  and 
Mills  of  Gilpin  County,  Colorado,"  Trans.  Amer.  Inst.  Min.  Eng.,  II.,  29. 
Further  references  will  be  found  under  "Silver  and  Gold  in  Colorado." 

^  T.  B.  Comstock,  First  Ann.  Rep.  Texas  Geol.  Survey,  1889,  p.  334.  W. 
F.  Cummins,  Idem,  196.  W.  H.  Streeruwitz,  in  Mineral  Resources  of  the 
U.  S.,  1884,  p.  342. 


COPPER.  205 

strongly  devreloped  on  the  south  shore  of  Lake  Superior,  espe- 
cially in  Keweenaw  Point,  which  juts  out  northeasterly,  cut- 
ting the  lake  into  two  nearly  equal  portions.  They  extend  some 
distance  east  and  west,  and  are  also  known  on  the  north  shore. 
They  consist  of  sandstone  and  thin  beds  of  conglomerate,  inter- 
stratified  with  sheets  of  diabase,-  both  compact  and  amygdaloi- 
dal,  and  of  melaphyre.  They  are  succeeded  on  the  east  by  the 
Eastern  Sandstone,  which  on  the  south  shore  is  thought  by 
Irving,  Chamberlin  and  others  in  some  places  to  abut  uncon- 
formably  against  them,  and  in  others  to  pass  under  them  from 
an  overthrust  fault.  Wadsworth,  however,  considers  that  the 
Eastern  Sandstone  passes  conformably  beneath  the  Keweena- 
wan,  and  that  it  is  older. 

The  Eastern  Sandstone  forms  a  comparatively  low,  flat  bench 
some  miles  across,  between  the  lake  and  the  ridge  of  the  Ke- 
weenawan,  whose  rocks  rise  quite  abruptly  in  a  marked  escarp- 
ment. The  several  streams  that  fall  over  this  scarp  in  cas- 
cades have  served  by  their  erosion  to  expose  the  contacts. 
The  best  known  are  the  Hungarian  and  Douglas  Houghton 
Rivers.  On  the  west  or  northwest  side  the  escarpment  is 
much  less  pronounced  and  the  contact  is  less  well  shown  and 
has  not  been  so  sharply  located.  The  sandstone  is  called  the 
Western  Sandstone.  It  is  now  pretty  well  shown  that  the 
Eastern  Sandstone  is  a  close  equivalent  to  the  Potsdam,  for 
though  itself  lacking  in  fossils,  it  is  known  to  pass  conformably 
beneath  fossiliferous  Lower  Silurian  limestone  near  L'Anse. 

On  Keweenaw  Point  the  beds  dip  northwesterly  and  pass 
under  Lake  Superior  to  reappear  with  a  southeasterly  dip  on 
Isle  Royale  and  the  Canadian  shore.  Western  Lake  Superior 
occupies  this  synclinal  trough.  In  Keweenaw  Point  the  dip  is 
greatest  on  the  southvest,  being  about  60°  at  Hancock.  To 
the  northeast  it  gradually  flattens  to  30°  or  less  on  the  lake 
shore.  (For  the  general  geology  of  the  neighboring  region  see 
under  Example  9.) 

It  is  interesting  to  note  that  the  early  investigators  of  the 
geology  of  this  country  drew  a  parallel  between  the  sandstones 
and  traps  of  Lake  Superior  and  the  similar  Triassic  deposits  of 
the  Atlantic  coast  (see  Example  21),  even  going  so  far  as  to 
regard  the  former  as  the  western  equivalent  of  the  latter.* 
»  C.  T.  Jackson,  Amer.  Jour.  Set.,  i.,  XLIX.,  1845,  pp.  81-93. 


306 


KEMP'S  ORE  DEPOSITS. 


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and  the  Ontonagon,  at  the  western  base.  Mines  have  also  been 
worked  on  Isle  Royale,  and  copper  is  fonnd  in  small  amounts  on 




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Fig.  66. — Map  of  the  Portage  Lake  IHstHct,  Keweenaw  Point,  Mwh.     Adap- 
ted from  a  map  in  the  catalogue  of  the  Michigan  College  of  Mines. 

the  north  shore.  The  Portage  Lake  district  is  now  the  princi- 
pal and  almost  the  only  producer.  In  the  first-named  district 
most  of  the  mines  are  on  original  fissures,  which  have  later 


^08  KEMP'S  ORE  DEPOSITS. 

become  much  enlarged  by  the  alteration  of  the  walls.  They 
are  usually  from  one  to  three  feet  broad,  but  may  reach  10,  20, 
and  30  feet,  this  last  in  the  more  loosely  textured  rocks.  These 
expansions  are  also  richer  in  copper.  The  veins  stand  nearlj^ 
vertical,  and  cross  the  beds  at^ight  angles.  They  were  the 
earliest  discovered,  and  the  fir^fljo  be  extensively  worked. 
The  metallic  masses,  both  large  and  small,  occur  distributed 
through  the  gangue.  The  best-known  mines  of  the  district  are 
the  Central,  Cliff,  Phoenix  and  Copper  Falls.  All  have  been 
recently  closed  except  the  Central,  which,  after  temporary  sus- 
pension in  1894,  resumed  operations  in  1896.  A  conglomerate 
appeared  to  cut  off  the  vein,  although  probably  a  fault  and  move- 
ment parallel  with  the  dip  occasioned  the  displacement.  With 
favorable  markets  several  other  vein  mines  maj"  be  intermit- 
tently worked.  The  vein  mines  have  been  the  great  source  of 
fine  minerals  in  the  past,  the  Phoenix  being  well  known  for 
its  zeolites. 

2.04.12.  In  the  Portage  Lake  district  the  mines  are  either  in 
conglomerate  (Calumet  and  Hecla,  Tamarack,  Peninsula,  etc.) 
or  in  amygdaloidal,  strongly  altered  diabase,  certain  very  sco- 
riaceous  sheets  of  which  are  known  as  ash-beds  (Quincy, 
Franklin,  Atlantic,  etc.).  In  the  conglomerates  the  copper  has 
replaced  the  finer  fragments,  so  as  to  appear  like  a  cement,  and 
often  the  boulders  themselves,  or  particular  minerals  in  them, 
are  permeated  with  copper.  The  rich  portions  are  of  limited 
extent  along  the  strike  as  they  give  way  to  barren  rock,  after 
a  stretch  it  may  be  of  several  thousands  of  feet,  and  they  go 
down  as  great  chutes  somewhat  diagonally  on  the  dip  to  very 
great  depths.  The  Tamarack  workings,  below  the  Calumet 
and  Hecla,  have  been  pushed  on  the  bed  nearly  a  mile  below 
the  outcrop,  and  show  no  diminution  or  essential  change  in 
the  copper  rock.  Three  copper- bearing  conglomerates  have 
been  identified,  the  Calumet  and  Hecla,  the  Albany  and  Bos- 
ton (also  called  the  Peninsula)  and  the  Allouez.  The  first  is 
much  the  richest,  but  has  not  been  found  productive  at  any 
other  point  on  the  strike  than  in  the  great  mine  which  gives  it 
its  name.  The  amygdaloids  have  copper  in  their  small  cavi- 
ties, but  in  the  open  or  shattered  rock  it  fills  all  manner  of 
irregular  spaces,  often  in  fragments  of  great  size.  It  is  asso- 
ciated  with  calcite,  zeolites,  datolite,  epidote,  and   a  chloritic 


COPPER.  209 

mineralj  or  "green  earth"  containing  Fe203.  The  distribution 
of  the  copper  in  the  amygdaloidal  sheets  is  much  the  same  as 
in  the  conglomerates.  It  is  limited  along  the  strike,  and  goes 
down  at  a  slight  diagonal  in  great  chutes  whose  ends  have 
never  yet  been  reached.  This  arrangement  must  have  an 
important  bearing  on  the  method  of  origin. 

2.04.13.  In  the  Ontonagon  district  the  copper  follows 
planes  approximately  parallel  to  the  bedding  of  the  sandstones 
and  igneous  rocks,  and  in  one  case  at  least  (the  National  mine) 
along  the  contact  between  the  two.  The  copper  is  quite  irregu- 
lar in  its  distribution,  but  has  the  same  associates  that  are 
mentioned  above. 

On  the  Origin  of  the  Copper. — The  original  source  of  the  cop- 
per was  thought  by  the  earlier  investigators  to  be  in  the  erup- 
tive rocks  themselves,  and  that  with  them  it  had  come  in  some 
form  to  the  surface,  and  had  been  subsequently  concentrated  in 
the  cavities.  Pumpelly  has  referred  it  to  copper  sulphides  dis- 
tributed .through  the  sedimentarj^  as  well  as  the  massive  rocks 
from  which  the  circulating  waters  have  leached  it  out  as  car- 
bonate, silicate,  and  sulphate.  Although  the  traps  are  said  by 
Irving  to  be  devoid  of  copper,  except  as  a  secoodary  introduc- 
tion, it  would  be  interesting  to  test  their  basic  minerals  for  the 
metal  in  a  large  way,  as  has  been  so  successfully  done  by  Sand- 
berger  on  other  rocks.  It  is  probable  that  these  may  be  its 
source. 

Irving  states  that  the  coarse  basic  gabbros  of  the  system  con- 
tain chalcopyrite,  but  they  do  not  occur  near  the  productive 
mines.  The  electro- chemical  hypothesis  of  deposition  was  ear- 
liest advocated  (Foster  and  Whitney),  and  on  account  of  the 
electrolytic  properties  of  the  two  metals  copper  and  silver,  at 
first  thought,  it  seems  to  be  a  reasonable  explanation.  Still,  the 
unsatisfactory  character  of  all  experiments  made  in  other  re- 
gions to  detect  such  action  militates  against  it.  Pumpelly, 
however,  has  worked  out  an  explanation  much  more  likely  to 
be  the  true  one.  He  found,  on  studying  the  mineralogical 
changes  which  have  taken  place  in  the  rocks,  that  the  altera- 
tion had  been  very  thorough,  and  that  it  had  involved  a  most 
interesting  series  of  minerals,  which  are  now  chiefly  mani- 
fested in  the  cavity  fillings.  It  is  to  be  appreciated,  as  has 
been   especially  well  shown   by  the  recent  detailed  geologi3al 


210  KEMP'S  OME  DEPOSITS. 

sections  of  L.  L.  Hubbard/  that,  in  the  productive  region,  the 
Keweenawan  rocks  consist  of  a  vast  series  of  basic  lava  flows, 
with  a  few  of  more  acidic  types,  and  with  occasional  intercalated 
conglomerates.  H.  L.  Smyth^  has  also  emphasized  the  fact 
that  these  successive  lava  sheets  must  have  remained  for  pro- 
tracted periods  after  their  outpourings,  exposed  to  the  atmos- 
pheric agents,  and  to  weathering,  befoWthey  sank  beneath  the 
sea,  and  were  buried  under  the  conglonifrates.  As  a  matter  of 
observation  the  upper  portions  of  the  sheets  are  notably  more 
cellular  and  decomposed  than  are  the  lower.  Two  kinds  of  amyg- 
daloids  were  indeed  recognized  by  Pumpelly,^  brown  ones,  or 
true  amygdaloids,  in  which  the  alteration  was  excessive,  and 
which  were  probably  derived  from  cellular  lava  sheets;  and 
green  ones,  or  pseudo-amygdaloids,  which  are  hard  and  dense, 
and  probably  owe  their  apparent  amygdules  to  the  decom- 
position of  pj'roxene,  olivine  or  feldspar  crystals.  Pumpelly 
traces  out  the  following  series  of  minerals.  The  first  to 
develop  was  chlorite.  Either  contemporaneously  with  the 
chlorite  or  next  after  it,  laumontite,  a  hydrated  basic 
silicate  of  calcium  and  aluminum,  resulted.  Laumontite, 
prehnite  and  epidote,  all  non-alkaline  silicates,  next  segre- 
gated in  the  cavities,  and  were  followed  by  quartz.  They 
are  thought  to  correspond  to  the  deoay  of  the  pyroxenic 
minerals  in  the  lavas.  The  copper  manifestly  came  in  after 
this,  and  its  deposition  seems  to  have  proceeded  along  with  the 
formation  of  a  green  chloritic  mineral,  or  green-earth,  which 
has  displaced  the  prehnite,  quartz  and  calcite  of  the  earlier 
stages.  Calcite,  it  should  be  added,  marks  almost  every  stage 
of  the  paragenesis.  Presumably  the  reducing  action  produced 
by  the  oxidation  of  FeO  to  Fe203  in  the  production  of  the  chlo- 
ritic '*  green -earth,"  caused  the  reduction  and  precipitation  of 
the  copper  from  some  aqueous  solution  of  sulphate,  carbonate 
or  silicate.  After  all  this  had  occurred  a  quite  different  series 
of  minerals  (except  that  calcite  continued  to  form)  was  intro- 
duced, which  are  characteristically  alkaline  silicates.     Anal- 

^  Geological  Survey  of  Michigan,  V.,  opp.  p.  166. 

»  Science,  February  14,  1896,  p.  251. 

'  Geological  Survey  of  Michigan,  I.,  Part  II.,  14.  Amer.  Jour.  Sci.,  Sep 
tember,  1871.  Proc.  Amer.  Acad.  Arts  and.  Sciences,  XIII.,  p.  268,  1878. 
Geol.  Wisconsin,  III.,  31. 


COPPER.  211 

cite,  apophy  llite,  datolite,  and  last  of  all  orthoclase,  are  the  chief 
members.  Pumpell}'  regards  them  as  produced  by  the  altera- 
tion of  the  feldspars  of  the  basalts,  and  in  a  continuous  succes- 
sion of  changes  following  those  just  cited,  but  H.  L.  Smyth 
advances  the  view  that  they  and  the  copper  came  in  after  the 
tilting  and  faulting  of  the  strata,  and  probably  in  uprising 
solutions  along  the  fissures,  which  are  illustrated  in  the  vein 
mines.  He  remarks  that  apoph3^11ite  contains  fluorine  and 
datolite,  boron,  and  that  the  mineralization  of  the  fissure  veins 
is  often  extended  in  lateral  enrichments,  where  the  fissures  cut 
porous  beds.  Pumpelly  specially  favored  the  overlying  sand- 
stones and  descending  solutions  as  sources  of  the  copper. 
Wadsworth  gives  a  resume  of  all  the  views  advanced  up  to 
1880^  and  himself  favors  a  derivation  by  leaching  of  the  neigh- 
boring and  overlying  trap. 

As  stated  in  mentioning  the  ^reat  ore-chutes  above,  the  cir- 
culations must  have  followed  the  general  lines  indicated  by 
them,  so  that  it  is  evident  that  the  rich  currents  were  of  lim- 
ited extent.  The  anomalous  condition  presents  itself  of  native 
copper,  a  mineral  that  is  usually  characteristic  of  the  oxidized 
zone  of  deposits  of  sulphides,  extending  to  great  depths  below 
the  ground-water  level. 

It  is  natural  to  rai§e  the  query  as  to  the  possible  passage  of 
the  native  copper  into  sulphides  in  depth,  but  there  is  as  yet 
no  evidence  of  this  change.  Any  minerals  in  the  nature  of 
sulphides  are  extraordinarily  rare.  A  little  whitneyite  and 
domeykite  (copper  arsenides)  and  chalcocite  occur  in  the 
amygdaloid,  formerly  worked  at  the  Huron  mine ;  chalcocite  has 
been  found  in  the  Bohemian  Mountains  and  in  the  Copper 
Falls  mine.  Native  copper  changes  to  chalcocite  90  feet  down 
in  the  Mamaisne  mine,  near  the  Sault  (L.  L.  Hubbard).  A 
pocket  of  melaconite,  the  black  oxide,  was  opened  in  the  early 
days  at  Copper  Harbor. 

2.04.15.  The  discovery  of  copper  dates  back  to  the  explora- 
tions of  the  French,  who,  in  the  seventeenth  century,  left  the 

*  M.  E.  Wadsworth,  "Notes  on  the  Geology  of  the  Iron  and  Copper 
Districts,"  Bull.  Mus.  of  Comp.  Zool,  VII.,  76,  123.  Report  of  the  State 
Geologist  of  Michigan,  1892,  167-170,  and  especially  169.  Rec.  Also  in  a 
pamphlet  of  the  Duluth,  South  Shore  &  Atlantic  R.  R.,  1890.  "Origin 
and  Mode  of  Occurrence  of  the  Lake  Sui^rior  Copper  Deposits, "  Trans. 
Amer.  Inst.  Min.  Eng.,  XXVII.,  669. 


212  KEMP'S  ORE  DEPOSITS. 

settlements  on  the  lower  St.  Lawrenco  and  penetrated  the  Great 
Lakes.  The  country  was  the  scene  of  a  great  mining  excite- 
ment in  the  forties.  After  many  vicissitudes  and  exploded 
schemes  the  district  settled  down  to  the  largest  production  of 
any  American  region.  WWithin  the  last  few  years,  however, 
Butte,  Mont.,  has  exceeded  it.  Many  interesting  traces  of  pre- 
historic mining  were  found  by  the  early  explorers,  for  the 
copper  was  a  much-prized  commodity  among  the  aborigines. 

2.04.16.  Some  important  mining  for  copper  has  been  done 
on  Isle  Royale,  along  the  Canadian  shore,  and  in  Minnesota, 
but  although  Keweenawan  rocks  are  in  great  force,  no  large 
amount  of  the  metal  has  been  found. ^ 

*  It  would  be  impossible  and  undesirable  to  give  in  this  place  complete 
references  to  the  literature.     Such  a  bibliography  will  be  found  in  Irving's 
monograph,  and  in  Wadsworth's.     The  more  important  papers  are  given 
below,  with  some  additions  to  the  lists  mentioned  above. 
Bauerman,  H.,  "On  the  Copper  Mines  of  Michigan,"  Quar.   Jour.  Geol. 

Soc,  XXII.,  448,  1866.     Good  account  of  the  minerals. 
Credner,  H.,  On  the  geology,  etc.,  Neues  Jahrbuch,  1839,  p.  1. 
Foster  and  Whitney,  Report  on  the  Lake  Superior  Copper  Lands,  1850. 
Hall,  C.  W.,    "A  Brief  History  of   Copper  Mining  in  Minnesota,"   Bull. 

Minn.  Acad.  Nat.  Sci.,  Vol.  III.,  No.  1,  p.  105. 
"History  of  Copper  Mining  in  the  Lake  Superior  District,"      Engineer- 
ing and  Mining  Journal,  March  18,  1882,  p.  141. 
Hubbard,   L.  L.,  "Two  New  Geological  Sections  of  Keweenaw  Point," 

Proc.  Lake  Sup.  Min.  Inst. ,  II.     Rec. 
Irving,  R.  D..  '.'The  Copper-bearing  Rocks  of  Lake  Superior,"  Monograph 

v.,  U.  S.  Geol.  Survey,  especially  p.  419.     Rec.     Bibliography,  p.  14. 
"  Keweenaw  Point  with  Particular  Reference  to  the  Felsites  and  their 

Associated  Rocks,"  Geol.  Survey  of  Mich.,  VI.,  Part  II.,  1899. 
Lane,  A.  C,  Geological  Report  on  Isle  Royale,  Mich.  Geol.  Survey,  Yl.,  Pt.  I. 
Lawson,  A.  C,  "  Notes  on  the  Occurrence  of  Native  Copper  in  the  Animi- 

kie  Rocks  of  Thunder  Bay,"  Amer.  Geol.,  V.,  174. 
Palache,  Ch.,  "The  Crystallization  of  Calcite  from  the  Copper  Mines  of 

Lake  Superior,"  Geol.  Survey,  Mich.,  VI.,  Part  II.,  Appendix. 
Poole,  H.,  "  Michipicoten  Island  and  its  Copper  Mines,"  Eng.  and  Min. 

Jour.,  August  6,  1892,  p.  125;  September  3,  p.  220. 
Pumpelly,  R.,  Geol.  Survey  of  Mich.,  1873,  Vol.  I. 

"On  the  Origin  of  the  Copper."  Amer.  Jour.   Sci.,  ii..  HI.,  183-195, 

243-253,  347-353.     Rec.     A  later  and  fuller  paper  is  in  Proc.  Amer. 

Acad.,  1878,  Vol.  XIII.,  p.  233. 
Rominger,  C,  "  Copper  Regions  of  Michigan,"  Geol.  Survey  of  Mich.,  V., 

85,  1895. 
Wadsworth,  M.  E. ,  Notes  on  the  Geology  of  the  Iron  and  Copper  DistHcts 

of  Lake  Superior.     Cambridge,   1880.     Bibliography,   p.   133.     See 

also  footnote  to  page  211  above. 


COPPER. 


213 


2.04.17.  Example  19.  St.  Genevieve,  Missouri.  Beds  of 
chalcopyrite  associated  with  chert  m  magDesian  limestone  of 
the  Cambrian  system.     St.  Genevieve  is  situated  on  the  Missis- 


2nd._M.agne3ian  Limestone 
^Roof 

Limestone 
J^>  Chert  seams 

Sulphuret  ore 

^Floor 

2nd.  Magnesian  Ll'mestoaa 


Fig.  67. — Cross  section  in  the  St.  Oenemeve  copper  mine,  illustrating  the  rela- 
tions of  the  ore.  After  F.  Nicholson,  Trans.  Amer.  Inst.  Min.  Eng.,  X.,  450. 

sippi,  about  forty  miles  south  of  St.  Louis.  The  Second  Magne- 
sian Limestone  of  the  Cambrian  outcrops,  with  the  Carbonif- 
erous on  the  north,  and  more  or  less  Quaternarj'  in  the  vicin- 


Limestone 

vv:  Chert  and 
ore 


Fig.  68. — Section  at  the  St.  Genevieve  mine,  illustrating  the  intimate  relations 
of  ore  and  chert.  After  F.  Nicholson,  Ivans.  Amer.  Inst.  Min.  Eng.,  X.,  451. 

ity.     There  are   two  nearly  horizontal   beds  of  ore,  of  widths 
varying  between  three   inches  and  several  feet.     They  lie  be- 

Whitney,  J.  D. ,  "  On  the  Black  Oxide  of  Copper  of  Lake  Superior, "  Proc. 
Boston  Soc.  Nat.  Hist.,  January,  1849,  p.  102;  Am,er.  Jour.  Sci.    ii., 
VIII.,  273. 
Metallic  Wealth  of  the  United  States,  p.  245.     Rec. 

Whittlesley,   C,   "On  Electrical  Deposition,"  Am,er.  Assoc.   Adv.   Sci., 
XXIV.,  60. 

Wright,  C.  E.,  and  Lawson,  C.  D.,  Mineral  Statistics  of  Michigan.    An- 
nual formerly  issued. 


214 


KEMP'S  ORE  DEPOSITS. 


tween  cbert  seams,  and  are  associated  with  ciay  and  sand. 
The  ore  is  thought  by  Nicholson  to  have  been  deposited  in  cavi- 
ties formed  by  dolomitization,  much  as  is  advocated  by 
Schmidt  for  the  lead  and  zinc  deposits  of  southwest  Missouri, 
and  as  is  described  under  Example  25.  For  ten  years  the 
mines  have  not  been  operated.^ 


Fig.  69. — Geological  map  of  the  Morenci  or  Clifton  copper  district  of  Arizona. 
After  A.  F.  Wendt,  Trans.  Amer.  Inst.  Min.  Eng.,  XV    23. 

2.04.18.  Example  20.  Arizona  Copper.  Bodies  of  oxi- 
dized copper  ores  in  Carboniferous  limestones,  associated  with 
eruptive  rocks.  In  addition  to  these,  which  are  the  most 
important,  there  are  veins  in  eruptive  rocks,  or  in  sandstones, 
or  ore  bodies  of  still  different  character  as  set  forth  under  the 
several  sub-examples.    The  copper  districts  are  nearly  all  in 

^  F.  Nicholson,  "Review  of  the  St.  Genevieve  Copper  District, "  Trans. 
Amer.  Inst.  Min.  Eng.,  X.,  444.  B.  F.  Shumard,  "Observations  on  the 
Geology  of  the  County  of  St.  Genevieve,  Missouri,"  Trans.  St.  Louis 
Acad.  Sci.,  I.,  40;  abstract  in  ^mer.  Jour.  Sci.,  ii.,  XXVIII.,  126. 


COPPBB. 


215 


the  southeastern  part  of  the  territory,  but  the  Black  range  is 
near  the  center. 


VONGFELUOW^<^HIUU 


Fig.  70. — Vertical  section  of  Longfellow  Hill,  Clifton  district,  Arizona.    After 
A.  F.  Wendt,  Trans.  Amer.  Inst.  Min.  Eng.,  XV.,  52. 


Pig.  71.— Horizontal  sections  of  Longfellow  ore  body.    After  A.  F.  Wendt, 
Trans.  Amer.  Inst.  Min.  Eng.,  XV.,  52. 


2.04.19.     Example    20a.     Morenci.     The  Morenci  district, 
known  also  as  the  Clifton  or  Copper  Mountain,  lies  in  a  basin, 


216 


KEMP'S  ORE  DEPOSITS. 


six  to  ten  miles  across,  whose  high  surrounding  hills  consist 
of  limestone,  probably  Lower  Carboniferous,  which  rests  on 
sandstone,  and  this  on  granite.  The  principal  mines  are 
grouped  about  the  town  of  Morenci.  Clifton  is  seven  miles 
distant  at  the  point  where  the  smelter  of  the  Arizona  Copper 
Company  is  located.  In  the  basin  is  a  mass  of  porphyry,  con  ■ 
taining  frequent  great  inclusions  of  limestone^  Felsite  or  por- 
phyry dikes  are  also  abundant  in  the  surrounjEng  sedimentary 
and  granite  rocks.  Several  miles  to  the  east  there  is  an  out- 
flow of  late  trachyte  and  evidence  of  recent  volcanic  action. 
From  this  it  appears  that  eruptive  phenomena  are  abundant 
and  widespread. 


Fig.  72. — Geological  section  of  the  Metcalf  mine,  Clifton  district,  Arizona. 
After  A.  F.  Wendt,  Trans.  Amer.  Inst.  Min.  Eng.,  XV.,  36. 


2.04.20.  The  ores  are  classified  by  Henrich  as  follows: 
1.  Contact  deposits.  These  occur  in  a  zone  of  decomposed 
and  kaolinized  porphyry,  between  a  bluish,  fine-grained  lime- 
stone, and  solid  porphyry.  Many  ore  bodies,  and  probably  the 
largest,  are  directly  on  the  limestone,  while  others  are  sur- 
rounded by  the  decomposed  porphyry.  As  included  masses  of 
limestone,  with  associated  ore,  are  found  in  the  decomposed 
porphyry,  it  is  probable  that  these  ore  bodies  may  have  origi- 
nally replaced  such.  The  ores  are  malachite,  azurite,  cuprite, 
with  some  metallic  copper  and  melaconite,  in  a  gangue  princi- 


COPPER  ^17 

pally  of  limonite.     Wad  is  also  frequent.     Much  clay  of  a 
residual  character  occurs  with  the  ores. 

2.  Deposits  in  limestone.  These  are  closely  associated  with 
the  first  class,  and  have  apparently  formed  as  outlying  bodies 
in  the  limestone,  as  they  are  connected  by  ore  channels  with 
the  principal  lines  of  circulation  along  the  contact.  They  ap- 
pear to  contain  more  wad  and  lime  than  the  typical  contact 
deposits. 

3.  Deposits  in  porphyry.  These  form  sheets  and  pockets  in 
porphyry,  or  impregnate  the  solid  rock  itself.  They  are  oxi- 
dized at  the  surface,  but  pass  in  depth  into  chalcocite.  The 
principal  gangue  is  kaolinized  porphyry.  The  impregnated 
porphyries  are  to-day  the  chief  ore  supply. 

According  to  Wendt  the  Coronado  vein  fills  a  longitudinal 
fissure  in  a  quartz  porphyry  dike.  It  afforded  chalcocite  above, 
but  passed  into  chalcopyrite  below.  Wendt  also  mentions  a 
group  of  veins  in  granite  that  likewise  afforded  chalcocite.^ 

2.04.21.  Example  206.  The  Bisbee  district,  called  also  the 
Warren  district,  is  situated  in  the  Mule  Pass  Mountains  in 
southern  Arizona,  near  the  Mexican  line.  The  range  runs  east 
and  west,  and  consists  of  beds  of  Lower  Carboniferous  lime- 
stone, dipping  away  from  a  central  mass  of  porphyritic  rock. 
The  ores  are  found  in  the  canons  on  the  south  side,  which  have 
been  formed  by  erosion,  along  the  contact  of  the  limestone  and 
porphyry.  They  are  of  the  same  oxidized  character  as  at 
Morenci,  and  in  the  important  mines  occur  in  limestone. 
James  Douglass  describes  them  as  being  situated  at  a  distance 
from  the  porphyry  of  perhaps  a  thousand  feet  or  more,  and  as 
forming  in  their  unaltered  state  huge  masses  of  pyrites  with 
copper  often  as  low  as  two  per  cent.  They  have  been  pro- 
duced, as  nearly  as  one  can  judge  by  replacement  of  the  lime- 
stone, through  the  agency  of  solutions,  which  brought  much 
siliceous  and  aluminous  matter  as  well.  It  is  natural  to  look 
to  the  porphyry  as  the  source  of  the  latter  material.     The  sul- 

^  J.  Douglass,  "Copper  Eesources  of  the  United  States,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XIX.  678,  1890.  Rec.  "Arizona  Copper  and  Copper 
Mines,"  Eng.  and  Min.  Jour.,  August  13,  1881,  p.  103.  "Clifton  Copper 
Mines  of  Arizona,"  i7)id,  February  21,  1880,  p.  133.  C.  Henrich,  "The 
Copper  Ore  Deposits  near  Morenci,  Ariz.,"  Ibid.,  March  26,  1887,  pp.  202, 
219.  Rec.  A.  Wendt,  "Copper  Ores  of  the  Southwest,"  Trans.  Amcr 
Inst.  Min.  Eng.,  XV.,  p.  23.     Rec. 


218  KEMP'S  ORE  DEPOSITS. 

phides  pass  in  alteration  into  bodies  of  oxidized  ore,  which  re- 
main in  the  midst  of  ferruginous  clay,  called  * 'ledge  matter'' 
by  Dr.  Douglass.  Thoroughly  oxidized  masses,  as  well  as  oth- 
ers  whose  outer  shell  is  alone  changed,  are  known.  Ooe  mass 
in  the  Czar  shaft  of  the  latter  cH^i^ter  is  estimated  at  1,000,- 
000  tons  of  ore.  The  degree  of  altwation  does  not  appear  to  be 
dependent  on  the  vertical  position,  as  bodies  of  sulphides  are 
known  to  be  higher  up  than  thoroughly  oxidized  masses,  but 
in  this  arid  region  the  ground-water  stands  at  a  very  consider- 
able depth,  and  appears  not  to  have  been  yet  actually  reached, 
although  much  trouble  is  caused  by  floods  during  periods  of 
rain.  Above  the  bodies  of  ore  empty  caves  are  usually  found, 
and  so  frequent  is  this  association  that  when  the  prospecting 
drifts  strike  a  cave  the  miners  immediately  sink  in  the  expec- 
tation  of  striking  an  ore  body  in  depth.  Sink-holes  on  the  sur- 
face have  been  successfully  used  as  guides  in  the  same  way. 
In  the  accompanying  picture  of  the  mine.  Fig.  73,  the  lime- 
stones dip  into  the  hill,  away  from  the  shaft,  and  the  ores  are 
found  in  them,  and  beneath  the  valley  below. 

The  rock  referred  to  as  porphyry  above  has  been  microscopi- 
cally determined  by  A.  A.  Julien  for  Arthur  Wendt  to  be  a 
quartz-porphyry  with  a  f elsitic  ground  mass  (felsite- porphyry  of 
Julien).  Its  contact  with  the  limestones  is  marked  by  a  zone 
of  kaolinization,  or  alteration,  and  is  not  sharp.  Positive  evi- 
dence of  contact  metamorphism  has  not  yet  been  recorded,  but 
the  effects  of  circulating  waters  are  pronounced.  The  results 
of  detailed  geological  study  of  the  region  will  be  awaited  with 
interest.^ 

^.04.22.  Example  20c.  Globe  District.  As  in  the  other 
districts  the  most  productive  mines  are  in  limestone  near  the 
contact  with  eruptive  rocks. 

1.  Contact  deposits  in  limestone.  At  the  Globe  mines  the 
Carboniferous  limestone  abuts  against  a  great  dike  of  diorite, 
while  trachyte  and  granite  are  near.  Along  the  contact  there 
is  abundant  evidence  of  thermal  action  in  the  kaolinized  rock. 

*  J.  Douglass,  "Copper  Resources  of  the  United  States."  Trans.  Amer. 
Inst.  Min.  Eng.,  XIX.,  678,  1890.  Rec.  "The  Copper  Queen  Mine,"  New 
York  meeting  of  the  Amer.  Inst.  Min.  Eng.,  February,  1899.  See  Eng. 
and  Min.  Jour.,  February  25,  1899,  p.  230.  A.  Wendt,  "Copper  Ores 
of  the  Southwest,"  Trans.  Amer.  Inst.  Min.  Eng.,  XV.,  p.  52.     Rec. 


3 


h 


COPPER.  2J9 

The  great  bodies  of  oxidized  ores  are  found  on  this  contact  and 
extend  out  into  the  limestone.  The  one  on  the  Globe  claim  is 
described  by  Wendt  as  resembling  a  great  chimney. 

2.  A  fissure  vein  in  sandstone,  containing  arsenical  and 
antimonial  copper  ores,  and  known  as  the  Old  Dominion,  was 
formerly  worked. 

3.  Fissure  veins  in  talcose  slate  and  gneiss,  and  filled  by  a 
quartz  gangue  with  bunches  of  malachite  and  azurite  (New 
York  and  Chicago  mines),  and  now  no  longer  worked. 

4.  Numerous  small  veinlets  forming  a  stockwork,  in  gneiss 
near  a  dike  of  diorite,  which  is  crossed  by  a  dike  of  trachyte. 
These  are  known  as  the  Black  Copper  Group.  The  ores  are 
too  low  grade  for  profitable  exploitation.  Of  greater  interest 
are  the  bodies  of  chrysocolla,  found  in  the  wash  down  the  hill 
from  the  outcrop  of  the  veins,  and  evidently  due  to  the  super- 
ficial drainage  of  the  stockworks.  Similar  bodies  of  ore, 
though  not  chrysocolla,  were  found  at  Rio  Tinto,  in  Spain.* 

2.04.23.  Example  20d.  Santa  Rita  District.  Although 
in  New  Mexico,  this  district  has  much  in  common  with  those 
already  mentioned.  A  great  dike  of  felsite  cuts  limestones, 
and  along  the  contact,  as  well  as  in  the  felsite  itself,  copper 
ores  are  found. 

1.  Contact  deposits  in  limestone.  These  afforded  the  usual 
oxidized  ores,  but  were  not  found  to  extend  to  any  great  depth, 
and  while  for  a  time  productive,  they  were  soon  exhausted. 

2.  Deposits  in  felsite.  These  consisted  of  pellets  and  sheets 
of  native  copper  in  the  dike  itself,  which  were  oxidized  to 
cuprite  near  the  surface.  (Cf.  Lake  Superior  amygdaloids, 
Example  18.)  They  were  worked  by  the  Mexicans  in  the  early 
part  of  the  present  century.*^ 

*  J.  Douglass,  "  Copper  Resources  of  the  United  States,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XIX.  678,  1890.  Rec.  "The  Globe  District,"  Eng.  and 
Min.  Jmir.,  April  9,  1881,  p.  243.  W.  E.  Newberry,  "Notes  on  the  Pro- 
duction of  Copper  in  Arizona,"  School  of  Mines  Quarterly,  VI.,  370.  A. 
Trippel,  "Occurrence  of  Gold  and  Silver  in  Oxidized  Copper  Ores  in 
Arizona,"  Eng.  and  Min.  Jour.,  June  16,  1883,  p.  435.  A.  Wendt,  "Cop- 
per Ores  of  the  Southwest,"  Trans.  Amer.  Inst.  Min.  Eng.,  XV.,  p.  60. 

'  A.  F.  Wendt,  "Copper  Ores  of  the  Southwest,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XV.,  27.  Wislizenus,  "On  the  Santa  Rita  Mines:  Memoir  of 
a  Tour  in  Northern  Mexico,  1846-47,"  p.  47;  Amer.  Jour.  Sci.,  ii..  VI., 
385,  1848 


220  KEMP'S  ORE  DEPOSITS. 

2.04.24.  Example  20e.  Black  Range  District.  This  is  now 
the  leading  copper  producer  of  Arizona,  and  has  come  intc 
great  prominence  within  a  few  years.  In  its  geological  rela- 
tions it  appears  to  be  more  like  the  California  deposits  than 
any  others,  but  there  are  as  yet  but  few  recorded  details.  It 
appears  that  there  is  a  great  dike  ofMnore  or  less  porphyritic, 
dark  green  rock  that  has  been  extensively  fractured  along  a 
broad  line  of  dislocation  for  several  miles.  The  fractured 
zone  strikes  north  10°  west,  and  outcrops  about  5,800  feet 
above  tide.  The  writer  has  examined  thin  sections  of  the  dike- 
rock,  which  is  locally  called  diorite,  but  the  specimens  at  hand 
were  too  thoroughly  decomposed  to  admit  of  close  identifica- 
tion. No  dark  silicates  were  visible,  and  chloritic  products 
alone  indicated   their  former  presence.     Broadly  rectangular 

•feldspars  were  the  chief  minerals,  but  they  w^ere  too  badly 
altered,  even  to  indicate  their  character,  although  no  positive, 
polysynthetic  twinning  could  be  detected.  Quartz  was  com- 
mon. In  depth  sheared  dike  rock  is  met  that  resembles  slate. 
The  ore,  which  embraces  both  bornite  and  chalcopyrite,  fills 
the  cracks  and  larger  fissures  and  impregnates  the  slaty  rock. 
There  is  some  galena  present,  and  earthy  lead  sulphate  has 
resulted  from  it  in  the  gossan.  The  ore  carries  both  gold  and 
silver.  The  inaccessible  situation  of  the  mines  long  hindered 
their  development,  but  now,  with  a  mountain  railway  to  give 
them  an  outlet,  they  are  very  productive.  They  are  operated 
by  the  United  Verde  Company,  and  are  about  20  miles  west  of 
Prescott.  ^ 

2.04.25.  Example  20/.  Copper  Basin.  Beds  of  closely  tex- 
tured conglomerate  and  sandstone,  resting  on  granite  and 
gneiss,  and  having  a  cement  of  copper  carbonates.  Copper 
Basin  lies  about  twenty  miles  southwest  of  Prescott,  and  is 
formed  by  a  depression  in  greatlj^  decomposed  granite,  which 
is  traversed  by  numerous  small  veinlets  of  copper  ores.  The 
granite  is  pierced  by  porphyry  dikes,  and  covered  by  the  sedi- 

*  J.  F.  Blandy,  "The  Mining  Region  Around  Prescott,  Ariz.,"  Trans. 
Amer.  Inst.  Min.  Eng.,  XI.,  286.  G.  K.  Gilbert,  ''On  the  General  Geology 
of  the  Black  Mountain  District,"  Wheeler's  Survey,  III.,  p.  35.  A.  R. 
Marvine,  "Brief  Details  of  the  Verde  Valley,"  Wheeler's  Survey,  III.,  p. 
209.  A.  F.  Wendt,  "  Copper  Ores  of  the  Southwest,"  Trans.  Amer.  Inst 
Min.  Eng.,  XV.,  63.     Rec. 


COPPER.  231 

mentary  conglomerates  and  sandstones  into  which  its  copper  is 
thought  by  Blake  to  have  partially  leached  and  precipitated  as 
a  cement.  Reference,  by  way  of  comparison,  may  be  made  to 
the  Lake  Superior  conglomerates,  in  which,  in  part,  the  native 
copper  serves  as  a  cement.^ 

2.04.26.  There  are  numerous  other  copper  districts  in  Ari- 
zona of  minor  importance,  or  entirely  undeveloped,  but  the  ex- 
amples above  cited  probably  illustrate  the  occurrences  quite 
fully.  Those  not  referred  to  are  of  sporadic  development. 
Copper  prospects  are  known  in  the  Grand  Canon  of  the  Colo- 
rado, and  have  received  some  attention.^  Mention  should  also 
be  made  of  the  mines  in  Lower  California,  opposite  Guaymas, 
a  brief  description  of  which  will  be  found  in  Wendt's  paper.^ 
The  copper  ores  impregnate  beds  of  submarine  volcanic  tuff, 
and  are  unique  in  their  geological  relations. 

Much  copper  is  now  met  in  depth  at  Leadville,  Colo.  The 
geology  of  the  mines  is  set  forth  under  Lead-Silver. 

2.04.27.  Example  20gr.  Crismon-Mammoth,  Utah.  In  the 
Tintic  district,  Juab  County,  are  three  great  ore  belts,  in  ver- 
ticallj'  dipping  dolomitic  limestone,  as  more  fully  set  forth 
under  "Silver"  (Example  35a).  One  of  these,  the  Crismon- 
Mammoth,  contains  ores  that  bear  silver,  gold,  and  copper  in 
proportions  of  about  equal  value.  They  have  been  a  very  diflS- 
oult  mixture  to  treat  successfully.  Of  late  considerable  copper 
has  been  produced,  placing  the  ore  deposits  among  those  deserv- 
ing mention.  The  Crismon-Mammoth  vein  or  belt  covers  a 
maximum  width  of  70  feet,  and  runs  500  feet  on  the  strike, 
dipping  75°  west.  The  ores  seems  to  have  been  deposited  along 
the  bedding  planes,  though  often  cutting  across  them.  The  pro- 
ductive portions  are  found  in  richer  chutes  or  chimneys,  amid 
much  low-grade  material  and  gangue,  and  are  of  all  shapes 
and  sizes,  from  25  feet  in  diameter,  down.     The  Copperopolis 

*  W.  P.  Blake,  "The  Copper  Deposits  of  Copper  Basin,  Arizona,  and 
their  Origin,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVII.,  479. 

'  J.  F.  Blandy,  "On  Arizona  Copper  Deposits,"  Eng.  and  Min.  Jour., 
1897,  Vol.  LXIV.,p.  97. 

^  See  also  M.  E.  Saladin,  "Note  sur  les  Mines  de  Cuivre  du  Boleo 
(Basse  CaX\torin&),"  Bull,  de  la  Societe  del  Industrie  Minerale,  3  Serie, 
VI.,  5,  283. 


222  KEMP'S  ORE  DEPOSITS. 

is  thought  to  be  od  the  same  belt,  and  is  a  neighboring  location 
of  similar  geological  structure  and  ores/ 

A  very  important  body  of  chalcocite  was  discovered  in  1898 
in  Bingham  Canon,  whose  geological  relations  are  similar  to 
those  described  for  the  lead-silver  ir^s  under  2.08.23.  Its  loca- 
tion was  on  the  Highland  Boy  clarai. 

2.04.28.  Wyoming,  Idaho,  Washington.  Oxidized  ores 
have  been  exploited  to  some  extent  at  the  Sunrise  mines,  in  the 
Laramie  Kange,  Wyoming.  Iron  ores  are  in  the  same  region 
(see  under  Hematite).  Other  copper  prospects  have  been  opened 
in  the  Wood  River  region  in  northern  Wyoming,  and  at  other 
points,  but  the  geological  relations  have  not  yet  been  described. 

2.04.29.  In  the  extreme  western  border  of  Idaho,  near  the 
Oregon  line,  the  Seven  Devils  district  has  been  located  and 
developed  to  a  considerable  degree.  Intrusions  of  diorite  have 
pierced  a  white  marble  and  upon  the  contacts  and  upon  in- 
clusions have  developed  extensive  aggregates  of  garnet,  epidote 
and  specular  hematite,  together  with  very  considerable  amounts 
of  bornite.  Green  prophj^ritic  dikes  are  also  present.  Lind- 
gren  regards  the  ore  as  formed  by  pneumatolytic  processes  set 
up  by  the  diorite.  As  also  remarked  by  Lindgren  the  type  of 
ore  body  is  known  in  Mexico,  and  indeed  a  number  of  cases 
have  come  to  the  notice  of  the  writer.^ 

Not  a  few  copper  prospects  have  been  located  in  Washington, 
but  they  are  as  yet  of  somewhat  undemonstrated  value.  North 
of  Lake  Chelan  in  the  Stehekin  district  copper  sulphides,  pyrites 
and  mispickel  impregnate  brecciated,  andesitic  dikes  in  marble.* 
A  vein  in  King  County*  is  described  as  occurring  in  syenite. 

2.04.30.  Example  21.  Copper  ores  in  Triassic  or  Permian 
sandstone.     They  occur  as   oxidized  ores,  with  native  silver, 

*  O.  J.  Hollister,  "Gold  and  Silver  Mining  in  Utah,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XVI.,  p.  10.  D.  B.  Huntley,  Tenth  Census,  Vol.  XIII.,  p.  456. 
A  report  on  the  Tintic  District  is  in  press  with  the  U.  S.  Geol.  Survey, 
but  is  not  available  at  this  writing. 

"^  R.  L.  Packard,  "On  an  Occurrence  of  Copper  in  Western  Idaho," 
Amer.  Joun.  Sci.,  October,  1895,  398.  W.  Lindgren,  "Copper  Deposits  of 
the  Seven  Devils,"  Mining  and  Scientific  Press,  Feb.  4,  1899,  125.     Rec. 

^  As  learned  from  the  writer's  friend,  Charles  Of,  from  whom  material 
has  been  obtained  and  examined. 

*  R.  H.  Norton,  "A  Washington  Copper  Deposit,"  Eng.  and  Min.  Jour., 
February  11,  1899,  173. 


COPPER. 


223 


and  chalcocite  in  contact  deposits  in  Triassic  and  Permian 
sandstones  at  their  junction  with  diabase  or  gneiss,  or  as  dis- 
seminated masses  replacing  organic  remains.  •  Copper  ores  are 
very  common  throughout  the  estuary  Triassic  rocks  of  the 
Atlantic  coast,  and  although  formerly  much  mined,  they  are 
'now  proved  valueless,  and  of  scientific  interest  only. 

2.04.31.  Example  21a.  Contact  deposits  in  sandstone  at  its 
junction  with  diabase.  These  include  the  New  Jersey  ores, 
vigorously  worked  before  the  Revolution.  They  consist  of  the 
carbonates,  of  cuprite  and  of  native  copper,  disseminated  through 
sandstone  near  the  trap.  The  Schuyler  mines,  near  Arlington, 
N.  J.,  and  several  other  openings  near  New  Brunswick,  N.  J., 
are  best  known.     These  Triassic  diabases  often  show  chalcopy- 


FiG.  14:.— Gross  section  of  the  Schuyler  Copper  mine,  New  Jersey,     a,  trap; 

b.  sandstone;  e,  shales;  the  black  shading,  copper  ores.     After 

N.  H.  Barton,  U.  S.  Geol.  Survey,  Bull.  67,  p.  57. 

rite,  and  it  is  probable  that  the  copper  came  from  this  or  from 
copper  in  the  augite  of  the  rock,  in  accordance  with  Sand- 
berger's  investigations.  The  deposits  are  unreliable,  and  ex- 
cept at  a  very  early  period  have  never  been  an  important  source 
of  ore. 

2.04.32.  Example  216.  Contact  deposits  in  sandstones  at  the 
junction  with  gneiss.  A  number  of  deposits  were  formerly 
worked  of  this  character,  especially  at  Bristol,  Conn.',  and  at 
the  Perkiomen  mine,  Pennsylvania.  The  mine  at  Bristol, 
Conn.,  is  a  well-marked  contact  deposit,  on  the  line  between 
the  Triassic  sandstone  and  the  schistose  rocks.  The  contact 
runs  northeast   and  southwest,  has  suffered  great  decomposi- 


224  KEMP'S  ORE  DEPOSITS. 

tion  from  mineral  solutions,  and  has  been  largely  kaolinized. 
A  broad  band  of  this  decomposed  material,  30  to  120  feet  wide, 
lies  next  the  sandstone,  and  contains  disseminated  ore.  Then 
follow  micaceous  and  hornbl^de  slates,  often  with  horses  of 
gneiss.  The  slates  are  mucJTbroken  by  movements  that  have 
formed  cavities  for  the  ores.  It  is  reasonable  to  connect  the 
stimulation  of  the  ore  currents  with  the  neighboring  trap  out- 
breaks. Unusually  fine  crystals  of  chalcocite  and  barite  have 
made  the  mine  famous  the  world  over.  While  at  one  time  a 
source  of  copper,  for  many  years  it  has  been  unproductive.^ 

2.04.33.  Example  21c.  Chalcocite  and  copper  carbonates 
replacing  vegetable  remains,  etc.,  in  the  Permian  or  Triassic 
sandstones  of  Texas,  New  Mexico,  and  Utah.  In  the  Permian 
of  northern  central  Texas  are  three  separate  copper- bearing 
zones,  forming  three  lines  of  outcrop  that  extend  in  a  general 
northeasterly  direction  over  a  range  of  about  three  counties. 
The  ore  is  largely  chalcocite  in  beds  of  shale,  and  often  re- 
places fragments  of  wood.     It  may  be  available  in  time.^ 

At  various  places  in  Utah  and  New  Mexico  (Abiquiu,  N.  M., 
Silver  Reef,  Utah),  the  sandstones,  as  reported  by  Newberry 
and  others,  have  copper  ores  disseminated  through  them  and 
deposited  on  fossils,  at  times  with  associated  silver  (Utah). 
The  copper,  whether  coming  from  the  waters  along  the  shore 
line  or  from  subterranean  currents,  was  precipitated  by  the 
organic  matter.  (See  also  under  *' Silver,"  in  Utah.)  These 
deposits  are  not  yet  sources  of  copper.^ 

^  L.  C.  Beck,  "Notice  of  the  Native  Copper  Ores,  Copper,  etc.,  near 
New  Brunswick,  N.  J.,"  Anier.  Jour.  Sci.,  l,  XXXVI.,  107.  G.  H.  Cook, 
Geol.  of  N.  J.,  1868,  p.  675;  also  L.  C.  Beck,  Ibid.,  218-224.  J.  G.  Perci- 
val,  Rep.  on  Geol.  of  Conn.,  p.  77.  C.  A.  Shaeffer,  "Native  Silver  in  New 
Jersey  Copper  Ore,"  Eiig.  and  Min.  Jour.,  February,  1882,  p.  90.  C. 
U.  Shepard,  Geol.  of  Conn.,  1837,  p.  47.  B.  Silliman  and  J.  D.  Whitney, 
' '  Notice  of  the  Geological  Position  and  Character  of  the  Copper  Mine  at 
Bristol,  Conn.,"  Amer.  Jour.  Sci.,  ii.,  XX.,  361.  J.  D.  Whitney,  Metallic 
Wealth.     Rec. 

^  W.  F.  Cummins,  "Report  on  the  Permian  of  Texas  and  its  Overlying 
Beds,"  First  Ann.  Rep.  Texas  Geol.  Survey,  p.  196.  J.  F.  Furman, 
"  Geology  of  the  Copper  Region  of  Northern  Texas  and  Indian  Territory," 
Trans.  N.  Y.  Acad.  Sci.,  1881-83,  p.  15. 

'  F.  M.  F.  Cazin,  "  The  Origin  of  the  Copper  and  Silver  Ores  in  Triassic 
Sand  Rock,"  Eng.  and  Min.  Jour.,  April  30,  1880;  December  11,  1880,  331. 
"The  Nacemiento  Copper  Deposits,"  Ibid.,  August  22,  1885,  p.  124.     A. 


COPPER.  225 

2.04.34.  Copper  production  in  1882,  1890  and  1897,  in  tons  of 
2,000  pounds  each: 

1882.  1890.  1897. 

Lake  Superior 28, 578  50, 372  72, 920 

Montana _..  4,529  56,490  118,579 

Arizona.......... 8,992  17,398  40,510 

Colorado 747  441  4,719 

New  Mexico. .. ., oo. 434          '         425               

California..... .„.„......  413  11  7,065 

Utah 303 1  503  1,927 

Elsewhere 1,412  3,906  2,874 

Copper  sulphate . 6,501 

45,408  129,546  255,095 

The  figures  indicate  in  general  a  vast  increase  in  production, 
and,  above  all,  the  advance  of  Montana.  For  detailed  statis- 
tics The  Mineral  Industry,  issued  annually  by  the  Scientific 
Publishing  Company,  New  York,  and  the  Annual  Reports 
of  the  Director  of  the  U.  S.  Geological  Survey  are  the  chief 
books  of  reference. 

W.  Jackson,  Rep.  Director  of  the  Mint,  1880,  p.  334.  J.  S.  Newberry, 
"  Copper  in  Utah,  Triassic  Sandstones,"  Eng.  and  Min.  Jour.,  Vol.  XXXI., 
p.  5.  Also  October  23,  1880,  p.  269;  January  1,  1881,  p.  4.  See  also  Tenth 
Census,  Vol.  XIII.,  Precious  Metals,  pp.  40,  478.  C.  M.  Rolker,  "The  Sil- 
ver Sandstone  District  of  Utah,"  Trans.  Amer.  Inst.  Min.  Eng.,  IX.,  21. 
R.  P.  Roth  well,  quoted  in  Tenth  Census,  Vol.  XIII.,  p.  478.  B.  Silliman, 
"The  Mineral  Regions  of  Southern  New  Mexico,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XVI.,  427. 


CHAPTER  V. 

LEAD   ALONE. 

2.05.01.  The  deposits  of  lead  are  treated  in  three  different 
classes,  according  as  they  produce  or  have  produced  lead  alone, 
lead  and  zinc,  or  lead  and  silver.  Of  late  years  the  lead-silver 
ores  have  been  the  gjyftt  source  of  the  metal.  Only  the 
southeast  Missouri  region  is  of  much  importance  among  the 
others,  although  considerable  lead  is  also  obtained  in  associa- 
tion v^ith  zinc. 

LEAD   SERIES. 

Ph.  S. 

Galena,  PbS 86.6  13.4 

Cerussite,  PbCO., 77. 5 

Anglesite,  PbSO^ 68.3  .... 

Pyromorphite,  Pb3P208+l/3PbCl2.  76.36 
Earthy  mixtures  of  these  last  three  and  limonite. 

2.05.02.  Example  22.  Atlantic  border.  Veins  of  galena 
in  the  Archean  rocks  of  the  States  along  the  Atlantic  border ; 
also  others  in  Paleozoic  strata,  as  described  in  the  sub- 
examples. 

2.05.03.  Example  22a.  Veins  in  gneiss  and  crystalline  lime- 
stone, sometimes  with  a  bariteor  calcite  gangue.  These  depos- 
its were  vigorously  exploited  forty  years  ago  or  more,  but  have 
since  been  of  small  importance  other  than  scientific.  They 
may  be  described  best  by  districts,  as  they  hardly  deserve  a 
greater  prominence. 

2.05.04.  (1)  St.  Lawrence  County,  New  York.  Veins  with 
galena  in  a  gangue  of  calcite  in  Archean  gneiss.  Those  near 
Rossie  are  perhaps  best  known,  especially  for  their  unusually 
interesting  calcite  crystals.  There  are  numbers  of  veins  in  the 
district  which  are  notable  in  that  the  galena  is  without  zinc  or 
iron  associates.    The  lead  carries  a  verv  small  amount  of  silver. 


LEAD  ALONE.  227 

not  enough  to  separate.  Hornblende  and  mica  schists  occur  in 
the  same  region,  and  the  Potsdam  sandstone  is  not  far  removed. 
A  few  minor  veins  cut  the  Trenton  limestone  near  Lowville, 
Lewis  County,  sometimes  with  fluorite  for  a  gangue/ 

2.05.05.  (2)  Massachusetts,  Connecticut  and  eastern  New 
York  Veins  of  galena  with  more  or  less  chalcopyrite  and 
pyrite  in  a  quartz  gangue  in  gneiss,  slates,  limestones  or  mica 
schists.  The  mines  near  Northampton,  Mass.,  w^ere  formerly 
well  known,  although  never  productive  of  a  great  deal  of 
metal;  but  as  there  is  a  large,  prominent  vein,  it  attracted 
attention.  There  are  numerous  others  in  the  same  region. 
Veins  also  occur  at  Middletown,  Conn.,  where  much  silver  is 
said  to  be  found  in  the  galena.  More  recently  (circa  1873)  at 
Newburyport,  Mass.,  argentiferous  galena  attracted  attention, 
but  was  not  of  any  importance.  Other  veins  are  known  at 
Lubeck,  Me.,  and  in  various  parts  of  New  Hampshire  and 
Vermont.  For  a  time  small  lodes  in  the  slates  of  Columbia 
County,  New  York,  were  unsuccessfully  exploited,  of  which 
the  Aocram  mine  is  of  historic  interest.  Although  these  galena 
veins  are  numerous,  they  are  not  to  be  taken  too  seriously.^ 

2.05.06.  (3)  Southeastern  Pennsylvania.  Veins  on  the 
contact  of  Archean  gneiss  and  Triassic  sandstone  and  diabase. 
These  were  referred  to  under  Example  216.  As  noted  by  Whit- 
ney, the  copper  is  especially  strong  in  the  sandstone,  and  the 
lead  in  the  gneiss.  Trap  dikes  are  abundant,  and  the  eruptive 
phenomena  in  connection  with  them  may  have  occasioned  the 
activity  of  the  circulations  which  filled  the  veins.  The  Wheat- 
ley  mine  is  best  known.     It  has  afforded  a  great  variety  of  lead 

^  L.  C.  Beck,  Mineralogy  of  New  York,  p.  45.  E.  Emmons,  "Geology 
of  the  Second  District,"  N  Y.  Geol  Survey,  1842.  G.  Hadley,  "Crystal- 
lized Carbonate  of  Lead  at  Rossie,"  Amer.  Jour.  Sei.,  ii.,  II.,  117.  F.  L. 
Nason,  "  Calcite  from  Rossie,"  Bull.  4,  N  Y.  State  Museum,  1888.  J.  D, 
Whitney,  Metallic  Wealth.     Rec. 

^  B.  K.  Emerson,  Geology  of  old  Hampshire  Co.,  Mass.,  comprising 
Franklin,  Hampshire  and  Hampden  counties.  Monograph  XXIX,  U.  S. 
Geol.  Survey.  See  also  Bulletin  1^6. — Idem.  C.  A.  Lee,  "Notice  of  the 
Ancram  Lead  Mine,"  Amer.  Jour.  Sci.,  i.,  VIII.,  247.  A.  Nash,  "Notice 
of  the  Lead  Mines  and  Veins  in  Hampshire  County,  Massachusetts," 
Amer.  Jour.  Sci.,  i.,  XIL,  238.  R.  H.  Richards,  "The  Newburyport  Silver 
Mines,"  Trans.  Amer.  Inst.  Min.  Erig.,  HI.,  443.  B.  Silliman,  at  South 
ampton,  Mass  Bruce' s  Journal  of  Mineralogy,  I.,  65.  J.  D.  Whitney, 
Metallic  Wealth. 


228  KEMP'S  ORE  DEPOSITS. 

minerals,  especially  pyromorphite.     The  mines  have  not  been 
worked  in  years/ 

2.05.07.  (4)  Davison  County,  North  Carolina.  Veins  in 
talcose  slate  were  formerly  exploited,  but  are  now  little  known, 
except  as  having  furnished  beautiful  crystals  of  oxidized  lead 
minerals.^ 

2.05.08.  Example  226.  Sullivan  and  Ulster  Counties,  New 
York.  Veins  along  a  Lne  of  displacement  on  the  contact 
between  the  Hudson  River  slates  and  the  sandstones  of  the  Me- 
dina stage  (Shawangunk  grit),  carrying  galena  and  chalcopy- 
rite  in  a  quartz  gangue;  or  else  gash  veins  filled  with  the  same 
in  the  grit.  These  mines  formerly  produced  considerable  lead 
and  copper,  but  are  now  best  known  for  the  excellent  quartz 
crystals  which  they  have  furnished  to  all  the  mineralogical  col- 
lections of  this  and  other  lands.^ 

2.05.09.  Example  23.  The  Disseminated  Lead  Ores  of 
Southeast  Missouri.  Gal*^na,  accompanied  by  varying  amounts 
of  nickeliferous  pyrite,  disseminated  through  dolomitic  lime- 
stone of  Lower  Silurian  or  Cambrian  age,  its  determination  be- 
ing in  dispute.  The  dolomitic  limestone  is  called  the  St.  Jo- 
seph limestone  by  Arthur  Winslow,*  who  considers  it  Lower 
Silurian.  C.  R.  Keyes^  has  designated  it  the  Fredericktown, 
and  classifies  it  with  the  Cambrian.  As  shown  in  the  accom- 
panying map,  which  is  based  on  one  by  Winslow,  the  mining 
districts  ai^distributed  along  a  line  running  west  of  north. 
At  the  nortj  is  Bonne  Terre,  the  most  productive  of  all  up  to 
the  present.  A  few  miles  south  is  the  Flat  River  district,  in- 
cluding Desloge.  The  next  is  Doe  Run,  and  then  after  a  con- 
siderable interval  Mine  la  Motte..  Recently  prospects  have 
been  opened  near  Fredericktown.  Much  drilling  has  been  done 
between  these  centers,  but  without  notable  results.  The  geo- 
logical relations  are  simple.     On  the  south  and  southwest  are 

^  H.  D.  Rogers,  Geol.  of  Penn.,  II.,  701;  also  ^mer.  Jour.  Sci.,  ii.,  XVI., 
422.     J.  D.  Whitney,  Metallic  Wealth,  p.  396. 

^  J.  C.  Booth,  "Analyses  of  Various  Ores  of  Lead,  etc.,  from  King's 
Mine,  Davison  County,  North  Carolina,"  Amer.  Jour.  Sci.,  i.,  XLI.,  348. 
W.  C.  Kerr,  Geol.  of  North  Carolina,  p.  289. 

"  J.  D.  Whitney,  Metallic  Wealth.  W.  W.  Mather,  N.  Y.  State  Survey, 
Report  on  First  District,  358. 

*  Bull  133,  U.  S.  Geol.  Survey,  p.  11. 

''  "Mine  la  Motte  Sheet,"  in  3Io.  Geol.  Survey,  Vol.  IX.,  Report  4,  p.  48. 


LEAD  ALONE. 


229 


the  Archean  granites,  porphyries  and  diabase  dikes,  earlier 
mentioned  in  connection  with  the  specular  hematites  of  Iron 
Mountain  and  Pilot  Knob.     Scattered  knobs  of  them  are  also 


GEOLOGICAL  MAP 
OF  THE 
Frcdeh  ViUageX  SOITHEASTERN  MISSOURI 

>i\DISSEJlINATED  LEAD  ORE  SIB-DISTRICT 

From  a  Colored  Map 
by  Arthur  Winslow 
1895. 

In  Bulletin  132 
U.S.  Geol.  Survey 


Potosi 
Limestone 
„^^^'  j^3  St.Joseph 
Silurian -|^^  Limestone 
^Cambrian?)! 


Fig.  75. 

met  to  the  eastward.  On  the  granites  and  porphyries  rests  the 
La  Motte  sandstone,  of  variable  thickness,  but  possibly  reach- 
ing 400  feet,  according  to  Winslow.  Conformably  on  the  sand- 


230  KEMP'S  ORE  DEPOSITS. 

stone  lies  the  St.  Joseph  dolomitic  limestone,  the  ore-bearing 
formation.  It  varies  from  200  feet  at  Mine  la  Motte  to  600 
feet  at  Bonne  Terre.  It  varies  from  shaly  to  massive'struct- 
nres,  and  is  often  coarsely  granular  in  texture.  In  rock  of 
the  latter  character,  and,  in  the  southern  districts,  usually  not 
far  above  the  sandstone,  is  found  tha  ore.  At  Bonne  Terre, 
however,  the  ore  is  a  long  distance  above  the  base.  The  ore  is 
galena,  often  mingled  with  more  or  less  pyrites,  and  as  a  rule 
it  is  disseminated  through  the  limestone  so  as  to  form  an  inte- 
gral part  of  the  rock.  It  also  forms  sheets  sometimes  along 
joints  and  stratification  planes,  and  seems  to  favor  the  darker 
or  more  bituminous  varieties  of  the  dolomite.  At  Mine  la 
Motte  certain  *' diggings"  or  mines  seem  to  have  some  connec- 
tion with  a  local  fault,  but  others  do  not  indicate  such  rela- 
tions, and  elsewhere  small  fissures,  or  joints,  often  so  tight  as 
only  to  be  revealed  by  the  dropping  of  water,  are  the  only 
cracks  of  an}^  kind  apparent.  The  St.  Joseph  formation  lies 
very  flat,  and  is  practically  devoid  of  fossils.  Above  it  comes 
a  cherty  limestone,  called  the  Potosi  by  Winslow  (Leseur  by 
Keyes).  It  is  widespread,  but  has  no  immediate  connection 
with  the  ore. 

The  ore  bodies  are  in  the  nature  of  impregnations  of  the  wall 
rock  which  extend  fairly  parallel  with  the  stratification  and 
are  of  varying  thickness.  They  fade  out  gradually  into  low 
grade  or  barren  rock.  They  may  be  cut  at  several  horizons  by 
the  shafts  or  drill  holes.  One  at  Bonne  Terre  has  been  mined, 
according  to  Winslow,  over  an  area  nearly  three-quarters  by 
one  half  of  a  mile,  and  ore  is  known  through  almost  250  feet 
vertical  thickness.  The  yield  to  date  has  been  about  a  quarter 
of  a  million  tons  of  lead.  Throughout  the  districts  the  shafts 
are  not  deep,  seldom  reaching  400  feet.  The  ore  as  mined  con- 
tains from  7  to  10  per  cent,  galena,  although  blocks  of  over 
a  ton  of  the  pure  sulphide  have  been  taken  out. 

The  formation  of  these  ore  bodies  is  a  very  obscure  question. 
The  writer  in  1887  applied  to  them  the  views  that  had  been 
early  advanced  by  Whitney  for  the  gash  veins  of  the  Upper 
Mississippi,  namely,  that  decaying  marine  vegetation  had  pre- 
cipitated the  sulphides  from  sea  water.  This  is  very  doubtful, 
as  traces  of  algae,  or  any  other  fossils,  are  extremely  rare. 
W.  P.  Jenney  in  1893  referred  them  to  solutions  uprising  along 


LEAD  ALONE.  231 

faults,  which  were  thought  to  cut  the  ore  bodies,  and  from 
which  the  mineralizing  waters  had  spread  laterally  through 
the  porous  beds.  The  fault  at  Mine  la  Motte  along  which  the 
ore  occurs  has  been  earlier  cited  as  giving  some  support  to 
this  view,  although  right  at  the  fault  the  ore  bodies  tend  to 
grow  lean.  Elsewhere  faults  are  insignificant  so  far  as  known. 
Winslow  favors  the  descent  of  solutions  from  above,  and  thinks 
that  the  sulphides  have  been  supplied  by  the  weathering  of 
overlying  strata,  now  in  large  part  removed.  These  regions 
have  been  land  since  the  early  Carboniferous  times,  and  the 
superficial  decay  has  been  enormous.  Lead- bearing  solutions, 
it  is  thought,  have  filtered  downward  through  the  joints,  faults 
and  small  cracks,  and  have  deposited  their  dissolved  materials 
by  replacement  of  the  limestone.  The  conduits  seem,  how- 
ever, insignificant  when  compared  with  the  ore  bodies,  and  it 
is  evident  that  all  the  explanations  thus  far  suggested  involve 
difficulties. 

In  the  Mississippi  Valley  in  this  portion  of  the  country  the 
Lower  Carboniferous  and  earlier  rocks  contain  lead  over  an 
area  of  more  than  3,000  square  miles.  Aside  from  these  dis- 
seminated ores,  zinc  is  always  associated  with  the  lead ;  but 
in  southeastern  Missouri  it  is  practically  unknown  in  the  depos- 
its of  the  disseminated  type.  There  are,  however,  in  the  neigh- 
boring districts  several  mines,  such  as  the  Valle,  which  are 
closely  analogous  to  the  gash  veins  later  described,  and  which 
do  contain  zincblende.  The  history  of  Mine  la  Motte  dates 
back  to  the  early  part  of  the  eighteenth  century,  when  this 
region  figured  largely  in  John  Law's  Mississippi  bubble.  The 
mine  is  said  to  have  furnished  lead  for  bullets  during  the  war 
of  the  Revolution.^ 

^  A  bibliography  of  the  lead  and  zinc  regions  of  Missouri,  by  Arthur 
Winslow,  will  be  found  in  the  Reports  of  the  Missouri  Geol.  Survey,  VII. , 
Part  II.,  p.  743.  It  conies  down  to  1894.  A  bibliography  of  Missouri 
geology  in  general  was  prepared  by  F.  A.  Sampson  and  issued  as  Bulletin 
2  of  the  Mo.  Geol.  Survey,  in  1890.  A  revised  edition  by  C.  R.  Keyes 
appears  in  Vol.  X.,  of  the  Survey,  p.  221,  and  comes  down  to  1896.  The 
more  important  or  the  more  recent  papers  are  given  below:  G.  C.  Broad- 
head,  '  The  Southeastern  Missouri  Lead  District,"  Trans.  Amer.  Inst.  Min. 
Eng.,  v.,  100.  Rec.  J.  R.  Gage,  "  Occurrence  of  Lead  Ores  in  Missouri," 
Idem,  III.,  116;  also  Geol.  Survey  of  Missouri,  1873-74,  pp.  30,  603.  W.  P. 
Jenney,  "The  Lead  and  Zinc  Deposits  of  the  Mississippi  Valley,"  Irans. 
Amer.  Inst.  Min.  Eng.,  XXII.,  171,  621,  1893.     J.  F.  Kemp,  "Notes  on  the 


232  KEMP'S  ORE  DEPOSITS. 

2.05.10.  The  great  increase  in  lead  production  in  the  United 
States  came  about  1880,  with  the  opening  of  the  Leadville  ore 
bodies.  From  1877  until  1881  Eureka,  Nev.,  was  an  important 
source,  but  since  then  it  has  greatly  declined.  Utah  has  pre- 
served a  fairly  uniform  production  since  the  early  seventies. 
Lead  from  all  sources  is  here  mentioned,  although  lead- 
silver  ores  are  subsequently  treated.  The  amounts  are  in 
tons  of  2,000  pounds.  For  detailed  statistics  see  the  annual 
volume  on  The  Mineral  Industry  (New  York:  Scientific 
Publishing  Companj^  and  the  Annual  Reports  o^  the  Director 
of  the  U.  S.  Geological  Survey.  The  figures  for  1896  are 
taken  from  the  Eighteenth  Annual  Report,  Part  V.,  p.  240. 

Missouri,  Kansas,  Wisconsin,  lUinois 27,690  55,000  51,887 

Colorado 35,674  60,000  44,803 

Nevada 16,659  2,500  1,173 

Utah „ 15,000  24,000  85,578 

Idaho,  Montana 24,000  57,732 

Elsewhere 2,802  15,994  6,323 

97,825  181,494  197,496 

From  80  to  85%  of  the  total  product  is  from  lead-silver  ores. 
Ore  Deposits,  etc.,  of  Southeastern  Missouri,"  aS'c/ioo?  o/iUfmes  Quarterly, 
October,  1887,74;  April,  1888,  212.  C.  R.  Keyes,  "  The  Mine  la  Motte 
Sheet,"  Geol.  Survey  of  Missouri,  IX.,  Report  4,  1896.  A.  Litton,  Second 
Ann.  Rep.  of  the  First  Geol.  Survey  of  Mo.,  12-64,  1854.  James  E.  Mills, 
Report  on  the  Mine  la  Mo  tie  Estate,  New  York,  1877.  H.  S.  Munroe,  "The 
New  Dressing  Works  of  the  St.  Joseph  Lead  Co.,  at  Bonne  Terre,  Mo.," 
Tran^.  Amer.  Inst.  Min.Eng.,  XVII.,  659,  1888.  J.  W.  Neill,  "Notes  on 
the  Treatment  of  Nickel-Cobalt  Mattes  at  Mine  la  Motte, "  Idem,  XIII. , 
634.  F.  Posepny,  *'0n  Mine  la  Motte,"  Genesis  of  Ore  Deposits,  p. 
107;  Trans.  Amer.  Inst.  Min.  Eng.,  XXIII.,  303,  1893.  H.  A.  Wheeler. 
"On  Southeast  Missouri  Lead  Mines,  The  Colliery  Engineer,  1892.  C. 
P.  Williams,  "Industrial  Report  on  Lead,  Zinc  and  Iron  in  Missouri," 
Jefferson  City,  1877.  Arthur  Winslow,  "Lead  and  Zinc  Deposits  of 
Missouri,"  2  vols.,  Missouri  Geol.  Survey,  VII.,  Parts  I.  and  II.,  1894. 
A  very  complete  book  on  lead  and  zinc  in  general.  Fairly  complete  bibli- 
ography. Part  II. ,  p.  743.  A  fuller  one  by  F.  A.  Sampson  will  be  found  in 
Bulletin  2  of  the  Mo.  Geol.  Survey,  1890.  Arthur  Winslow,  "Lead  and 
Zinc  Deposits  of  Missouri,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXIV.,  634, 
931,  1894.  '  *  Notes  on  the  Lead  and  Zinc  Deposits  of  the  Mississippi  Valley 
and  the  Origin  of  the  Ores,"  Jour.  Geol,  L,  612,  1893.  "Report  on  the 
Iron  Mountain  Sheet,"  Mo.  Geol.  Survey,  IX.,  Report  3,  p.  32,  relates  to 
Doe  Run.  " The  Disseminated  Lead  Ores  of  Southeastern  Missouri,"  Bid- 
letin  132,  U.  S.  Geol.  Survey,  1896.  Rec.  The  best  brief  account,  "His- 
torical Sketch  of  Lead  and  Zinc,"  Eng.  and  Min.  Jour.,  November  17,  24, 
1894;  January  19,  1895. 


CHAPTER  VI. 

LEAD      AND      ZINCo 

2.06.01.  Example  24.  The  Upper  Mississippi  Valley. 
Gash  veins  and  horizontal  cavities  (flats),  principally  in  the 
Galena  and  Trenton  limestones  of  the  Upper  Mississippi  Val- 
ley, and  containing  galena,  zincblende,  and  pyrite  (or  marca- 
site),  with  calcite,  barite,  and  residual  clay.  The  deposits  are 
found  in  southwest  Wisconsin,  eastern  Iowa,  and  northwestern 
Illinois.  The  greater  portion  of  the  productive  territory  lies  in 
Wisconsin,  and  covers  an  area  which  would  be  included  in  a 
circle  of  sixty  miles  radius,  whose  limits  would  pass  a  few 
miles  into  Illinois  and  Iowa.  A  low  north  and  south  geanti- 
cline runs  through  central  Wisconsin,  dating  back  to  Arche- 
an  times  and  called  by  Chamberlin  *' Wisconsin  Island." 
On  its  western  slope  the  Cambrian  and  Lower  Silurian  rocks 
are  laid  down,  and  these  in  the  western  limit  of  the  lead  dis- 
trict pass  in  the  adjoining  States  under  the  Upper  Silurian. 
They  are  folded  also  in  low  east  and  west  folds,  but  in  the  aggre- 
gate the  whole  series  dips  very  gradually  westward.  The  chief 
east  and  west  fold  forms  the  south  bank  of  the  Wisconsin 
River,  and  may  have  been  the  cause  that  deflected  it  from  a 
southerly  course.  The  easterly  part  of  the  lead  region  is  350 
feet  higher  than  the  western,  and  the  northern  is  500  feet  above 
the  southern.     The  general  slope  is  thus  southwesterly. 

2.06.02.  The  Galena  limestone  is  a  dolomite  reaching  250  feet 
in  thickness.  On  the  hilltops  left  by  erosion  Maquekota  (Hud- 
son River)  shales  are  seen.  The  Galena  has  shaly  streaks, 
which  have  largely  furnished  the  residual  clay  of  the  cavities. 
There  are  also  cherty  layers  and  sandy  spots.  Under  the  Ga- 
lena lies  the  Trenton,  from  40  to  100  feet  thick,  and  made  up 
of  an  upper  blue  portion,  which  is  a  pure  carbonate  of  lime, 


23i 


KEMP'S  ORE  DEPOSITS. 


and  a  lower  bnff  portion  that  is  magnesian.  The  upper  portion 
of  the  blue  has  a  band  of  shale  locally  called  the  "  Upper  Pipe 
Clay,"  and  the  pure,  cpyptocrystalline  limestone  under  this  is 
called  *'Glass  Rock."  The  blue  contains  much  bituminous 
matter.  The  buff  is  locally  called  *' Quarry  Rock,"  and  is 
prolific  in  fossils.  Under  the  Trenton  lies  the  St.  Peter's  sand- 
stone, 150  feet  below  which  is  the  Lower  Magnesian  (Oneota), 
100  to  250  feet,  and  still  lower  the  Potsdam,  averaging  700  to 
800  feet.  The  Potsdam  rests  on  the  quartzites  and  schists  of 
the  Archean.    The  ore  bodies  especially  favor  the  shallow,  syn- 


^^SPSs^^^s 


'-^:!^ji^» 


:-^iii^ 


■   Fig.  76. — Gash  veins,  fresh  and  disintegrated.     The  heavy  black  shading  in- 
dicates galena.     After  T.  C.  Chainberlin,  OeoL  Wis.,  Vol.  IV.,  454. 

clinal  depressions  of  the  east  and  west  folds.  They  occur  in 
crevices,  the  great  majority  of  which  run  east  and  west.  The 
productive  ground  comes  in  spots,  which  are  separated  by 
stretches  of  barren  ground.  The  lead  ores  are  chiefly  produced 
by  the  crevices  in  the  Upper  Galena.  In  the  Lower  Galena 
the  zinc  ores  become  relatively  more  abundant,  and  they  are 
also  in  the  Trenton.  The  ores  do  not  extend  in  any  apprecia- 
ble amounts  either  above  or  below  these  horizons.  The  upper 
deposits  favor  the  vertical  gash  vein  form ;  the  lower  tend 
rather  to  horizontal  openings,  called  flats,  which  at  the  ends 


1 


LEAD  AND  ZINC. 


2;J5 


dip  down  (pitches)  and  often  connect  with  a  second  sheet  (flat) 
lying  lower.  There  are  several  minor  varieties  of  those  tw6 
main  types  of  cavity,  which  mainly  depend  for  their  differences 
on  the  grade  of  decomposition,  which  the  walls  have  under- 
gone, and  whether  there  was  an  original  opening,  or  only  a 
brecciated  and  crushed  strip.  Chamberliu  cites  twelve  varie- 
ties in  •^.11,  some  of  which  are  based  on  rather  fine  distinctions. 
A.  G.  Leonard  has  described  a  sheet  of  galena,  at  the  Lansing 
mine,  in  Iowa,  that  was  three  to  four  inches  thick,  25  to  35  feet 
high,  and  over  1,000  feet  long.  Some  of  the  Iowa  crevices  have 
proved  remarkably  persistent  on  the  strike.  H.  F.  Bain  has 
called  the  writer's  attention  to  the  Lansing  mine  in  Allamakee, 
Iowa,  which  has  yielded  lead  ore  without  any  zinc  whatever, 


Fig. 


77. — Idealized  section  of  ''flats  and  pitches,''  forms  of  ore  bodies  in  Wis- 
consin.    After  T.  C.  Chamherlin,  Geol.  Wis.,  Vol.  IV.,  458. 


and  which  is  peculiar  in  that  it  occurs  in  the  Oneota  or  Lower 
Magnesian  limestone,  and  is  therefore  below  the  main  product- 
ive horizon  of  the  gash  veins.  The  crevice  also  trends  north 
and  south  as  against  the  usual  east  and  west  strike  of  the  gash 
veins. 

2.06.03.  The  cavities  were  referred  by  J.  D.  Whitney  to 
joints,  formed  either  by  the  drying  and  consolidating  of  the 
rock,  or  by  gentle  oscillations  of  the  inclosing  beds.  The  later 
work  has  largely  corroborated  this,  and  they  are  generally 
thought  to  be  chiefly  caused  by  the  cracks  and  partings  formed 
by  the  gentle  synclinal  foldings.  Such  cavities  have  usually 
been  enlarged  by  subsequent  alteration  of  the  walls.     Whitney 


236  KEMP'S  ORE  DEPOSITS. 

also  esseotially  outlined  the  explanation  of  origin,  which  ha» 
been  more  fully  elaborated  by  Chamberlin.  Both  these  writ- 
ers have  urged  that  the  ores  could  not  have  come  from  below, 
for  the  lower  rocks  are  substantially  barren  of  them.  The  con- 
clusion therefore  follows  that  they  were  deposited  in  the  lime- 
stones at  the  time  of  their  formation.  The  source  of  the  ores 
is  placed  in  the  early  Silurian  sea,  from  which  it  is  thought  they 
were  precipitated  by  sulphuretted  hydrogen,  exhaled  by  decay- 
ing seaweeds,  or  similar  dead  organisms  on  the  bottom.  In 
carrying  the  idea  further,  Chamberlin  has  endeavored  to  re- 
produce the  topography  of  the  region  in  the  Lower  Silurian 
times  and  to  indicate  the  probable  oceanic  currents.  These  are 
conceived  to  have  made  an  eddy  in  the  lead  district,  and  to 
have  collected  there  masses  of  seaweed,  etc.,  resembling  the 
Sargasso  Sea.  While  interesting,  this  must  be  considered 
very  hypothetical.  When  the  sulphides  became  precipitated 
they  were  doubtless  finely  disseminated  in  the  rock,  and  were 
gradually  segregated  in  the  crevices.  The  sulphurous  exhala- 
tions from  the  bituminous  limestones  may  have  aided  in  their 
second  precipitation.  W.  P.  Jenney  in  1893  referred  the 
east  and  west  fissures,  mentioned  above  as  crevices,  to  fiaults, 
which  are  as  a  rule  not  far  from  the  vertical,  but  may  dip  35^ 
to  40°.  The  smaller  north  and  south  series  are  considered  to  be 
likewise  due  to  faulting,  but  to  be  earlier,  as  they  are  thrown 
by  the  east  and  west  set.  The  displacement  from  the  latter  is 
horizontal  rather  than  vertical.  The  intersections  of  the  two 
sets  are  said  to  be  especially  favorable  to  ore  bodies.  The 
name  **run"  is  applied  to  the  ore  body,  it  having  been  adopted 
from  southwest  Missouri.  The  ore  is  thought  to  have  been 
deposited  along  the  fault  fissures  by  uprising  solutions,  which 
have  spread  laterally  into  those  beds,  that,  from  their  chemical 
composition  (being  dolomitic)  or  their  open  structure,  were  fa- 
vorable to  them. 

In  the  same  year  (1893),  W.  P.  Blake  discussed  these  ore 
bodies,  paying  a  tribute  to  Percival's  early  views  on  faulting 
as  a  cause  of  the  veins,  and  describing  its  obscurity  and  the 
difficulty  of  demonstrating  its  presence.  Blake,  however,  cited 
the  Helena  mine  near  ShuUsburg  as  an  instance  in  which  the 
mineralization  did  occur  near  a  pair  of  faults.  Blake  also  lays 
stress  upon  the    presence   of  thin   seams   of  rich   bituminous 


LEAD  AND  ZINC.  237 

«hale,  ID  layers  usually  about  as  thick  as  cardboard,  which 
occur  in  a  richly  fossiliferous  limestone  at  the  top  of  the 
Trenton,  just  beneath  the  ore- bearing  '* Galena"  dolomite,  and 
which  are  regarded  as  very  probable  factors  in  the  precipita- 
tion of  the  ore. 

The  mining  region,  it  should  be  emphasized,  lies  within  the 
peculiar,  unglaciated  area,  which  is  one  of  the  notable  geologi- 
cal features  of  this  portion  of  the  country.  It  has,  therefore, 
long  been  exposed  to  the  atmospheric  agents,  and  has  not  been 
denuded  of  the  residual  products  of  decay  as  have  the  glaciated 
districts. 

The  papers  of  Jenney  and  Blake  led  to  a  notable  discussion 
of  these  ore  bodies,  and  to  wide  divergence  of  views  regarding 
them.  Arthur  Winslow,  in  connection  with  his  more  extended 
treatment  of  those  in  Missouri,  has  urged  that  the  sulphides 
have  been  supplied  from  the  overlying  strata,  during  the  exten- 
sive, subaerial  decay  to  which  these  have  been  subjected.  Pass- 
ing into  solution  they  are  thought  to  have  percolated  into  the 
crevices  and  to  have  been  precipitated.  A.  G.  Leonard,  in  his 
study  of  the  Iowa  veins,  reaches  a  similar  conclusion,  but  on 
account  of  the  impermeability  of  the  Maquekota  shales,  restricts 
the  source  of  the  ore  to  the  Galena  dolomite.  The  frequent 
occurrence  of  the  ores  in  stalactites  projecting  downward  from 
the  roof  of  a  chamber  gives  support  to  these  views.  Leonard 
favors  Chamberlin's  view  of  the  precipitation  from  a  sup- 
posed Sargasso  Sea  of  the  Ordovican  times. 

The  paragenesis  of  the  minerals  shows  the  following  suc- 
cession: (1)  Pyrite,  (2)  Galena,  (3)  Pyrite;  or  (1)  Pyrite,  (2) 
Blende,  (3)  Galena,  (4)  Pyrite;  or  (4)  Calcite.  The  ores,  espe- 
cially of  zinc,  are  often  oxidized,  and  afford  considerable  cala- 
mine and  smithsonite.  Some  oxidized  copper  ores  are  produced 
at  Mineral  Point,  formed  by  the  alteration  of  chalcopyrite.  In 
the  early  mines  lead  alone  was  sought,  but  of  late  years  the 
zinc  has  been  produced  in  greater  quantities,  and  is  more  valu- 
able than  the  lead.^  Smithsonite  is  found  in  commercial  quan- 
tities as  well  as  blende. 

'  Wisconsin.— J.  A.  Allen,  "Description  of  Fossil  Bones  of  Wolf  and 
Deer  from  Lead  Veins.",  Amer.  Jour.  Sci.,  iii.,  II.,  47.  W.  P.  Blake,  "The 
Mineral  Deposits  of  Southwest  Wisconsin,"  Trans.  Amer.  Inst.  Min. 
Eng.,  XXII.,  558,  1893.     Rec.     Amer.   Geol,  XII.,  237,  1893.     "The  Ex- 


238  KEMP'S  ORE  DEPOSITS, 

2.06.04.  Example  24a.  WashiDgton  County,  Missouri, 
Gash  veins  in  the  Potosi  cherty  limestone  of  eastern  Missouri 
in  the  same  region  as  the  disseminated  ores  of  Example  23,  and 
containing  galena,  barite  (locally  called  "tiff"),  calcite,  and 
residual  clay.  The  cavities  are  described  by  Whitney  as  re- 
sembling in  all  respects  the  gash  veins  further  north,  which, 
however,  lie  in  rocks  higher  in  the  geological  series.  These 
mines  were  the  earliest  worked,  but  have  been  given  up  since  the 

istence  of  Faults  and  Dislocations  in  the  Lead  and  Zinc  Regions  of  the 
Mississippi  Valley,  with  Observations  upon  the  Genesis  of  the  Ores,"  Idem, 
621.  Rec.  This  last  paper  was  written  in  discussion  of  one  by  W.  P. 
Jenney,  cited  below.  "Wisconsin  Lead  and  Zinc  Deposits, "  Bull.  Geol. 
Soc.  Amer.,  V.,  25,  1893.  "Progress  of  Geological  Surveys  in  the  State  of 
Wisconsin — a  Review  and  a  Bibliography,'  Trans.  Wis.  Acad.  Sci.,  IX., 
325.  T.  C.  Chamberlin,  Wis.  Geol.  Survey,  IV.,  1882,  p.  367.  Rec. 
E.  Daniels,  "  Geology  of  the  Lead  Mines  of  Wisconsin,"  Amer.  Asso.  Adv. 
Sci.,  VII.,  290;  Wis.  Geol.  Survey,  1854;  Eng.  and  Min.  Jour.,  July  6,  13, 
20,  27,  August  3,  10,  24,  October  5,  1878,  December  14,  1889,  522.  James 
Hall,  "Notes  on  the  Geology  of  the  Western  States,"  Amer.  Jour.  Sci.,  i., 
XLII.,  51.  W.  H.  Hobbs,  "A  Contribution  to  the  Mineralogy  of  Wiscon- 
sin," Bull.  Univ.  of  Wis.,  Science  Series  I.,  114;  see  sdso  Zeitsch.  fiir  Kryst., 
XXV.,  257,  1895.  J.  T.  Hodge.  "On  the  Wisconsin  and  Missouri  Lead 
Region,"  Amer.  Jour.  Sci.,  i.,  XLIII.,  35.  R.  D.  Irving,  "Mineral  Re- 
sources of  Wisconsin,"  Trans.  Amer.  Inst.  Min.  Eng.,  VIII.,  478.  E. 
James,  "Remarks  on  the  Limestones  of  the  Mississippi  Valley  Lead 
Mines,"  Phila.  Acad.  Sci.,  V.,  Part  I.,  p.  51.  W.  P.  Jenney,  "The  Lead 
and  Zinc  Deposits  of  the  Mississippi  Valley,"  Trans.  Amer.  Inst.  Min.  Eng., 
XXII.,  171,  621,  1893.  Rec.  J.  Murrish,  Report  on  the  Lead  Regions, 
1871,  as  commissioner  for  their  survey.  D.  D.  Owen,  "Report  on  the  Lead 
Region,"  U.  S.  Senate  Documents,  1844.  J.  G.  Percival,  Wis.  Geol.  Sur- 
vey, 1856.  Squier  and  Davis,  ''HistoricaX  Account,"  Smithsonian  Contri- 
butions, Vol.  I.,  p.  208.  M.  Strong,  Wis.  Geol.  Survey,  1877,  I.,  637;  II., 
645,  689.  J.  D.  Whitney,  Wis.  Geol.  Survey,  1861-62,  I.,  221.  Rec.  Me- 
tallic Wealth,  p.  403,  1856.  "On  the  Occurrence  of  Bones  and  Teeth  in 
the  Lead- bearing  Crevices,"  Amer.  Assoc.  Adv.  Sci.,  1859.  Arthur  Wins- 
low,  "Lead  and  Zinc  Deposits  of  Missouri,"  Trans.  Amer.  Inst.  3Iin.  Eng., 
XXIV.,  especially  677-690,  1894.  See  also  Vol.  VI.  of  Geol.  Survey  of 
Mo.,  135-150,  1894. 

Illinois.— J.  Shaw,  Geol.  Survey  of  Illinois,  1873,  II.,  340.  J.  D. 
Whitney,  Idem,  1866,  I.,  153. 

Iowa. — A.  G.  Leonard,  "Lead  and  Zinc  Deposits  of  Iowa,"  Iowa  Geol. 
Survey,  VI.,  1896.  Rec.  "  Origin  of  the  Iowa  Lead  and  Zinc  Deposits," 
Amer.  Geol,  XVI.,  288,  1895;  Eng.  and  Min.  Jour.,  June  27,  1896,  614; 
Colliery  Engineer,  XVII.,  121,  1896.  C.  A.  White,  Iowa  Geol.  Survey,  1870. 
II.,  p  339.     J.  D.  Whitney,  Idem,  1858,  L,  p.  422. 


LEAD  AND  ZING.  239 

price  of  lead  has  been  at  present  figures  (1875  and  subse- 
quently). The  ore  was  obtained  from  pockets,  caves,  irregular 
cavities,  and  from  the  overlying  residual  clays.  This  whole 
region  has  been  exposed  and  above  water  since  the  close  of 
Carboniferous  times,  and  has  suffered  enormous  surface  decay 
(seeR.  Pumpelly,  Tenth  Census,  Vol.  XV.,  p.  12,  and  Geol. 
Soc.  Amer.,  Vol.  II.,  p.  20),  which  has  left  a  mantle  of  residual 
clay  spread  widely  over  its  extent.  In  this,  more  or  less  float 
mineral  occurred.  The  mines  were  located  in  Washington, 
Franklin,  Jefferson  and  St.  Francois  counties.^  Very  similar 
deposits  in  rocks  of  about  the  same  geological  horizon  also 
occur  in  the  central  part  of  the  State,  in  the  counties  near  the 
Osage  River.  The  district  has  been  called  the  Central  by 
Winslow. 

2.06.05.  Example  246.  Livingston  County,  Kentucky. 
Veins  in  limestone  of  the  St.  Louis  stage  of  the  Lower  Carbon- 
iferous, containing  galena  in  a  gangue  of  fluorite,  calcite  and 
clay.  The  ore  bodies  have  never  been  well  described,  and  no 
very  accurate  account  can  be  given.  They  are  found  in  Liv 
ingston,  Crittenden,  and  Caldwell  counties,  Kentucky,  in  that 
portion  of  the  State  lying  south  of  the  Ohio  River  and  east  of 
the  Cumberland.  While  limestone  always  forms  one  wall,  a 
sandstone  of  geological  relations  not  well  determined  forms  the 
other.  The  veins  run  frorn  two  to  seven  feet  wide  and  in  in- 
stances are  richer  in  their  upper  portions  than  in  the  lower. 
As  yet  they  are  of  greater  scientific  than  practical  importance. 
Some  galena  occurs  also  in  irregular  cracks  in  the  limestone. 
As  a  possible  indication  of  a  stimulating  cause  for  the  forma- 
tion of  the  veins,  the  interesting  dike  of  mica-peridotite  may 
be  cited,  which  has  been  described  by  J.  S.  Diller.^  The  dike 
occurs  in  the  same  fissure  with  a  vein  of  fluorspar.^ 

^  Compare  the  older  references  under  Example  23,  and  the  following: 
A.  Litton,  Second  Ann.  Rep.  Missouri  Geol  Survey,  1854.  J.  D.  Whitney, 
Metallic  Wealth,  p.  419.  Arthur  Winslow,  "Lead  and  Zinc  Deposits  of 
Missouri,"  Vols.  VI.  and  VII.  of  Mo.  Geol.  Survey;  Trans.  Amer.  Inst. 
Min.  Eng.,  XXIV.,  634. 

^  "Mica-Peridotite  from  Kentucky,"  Amer.  Jour.  Sci.,  October,  1892. 

^  S.  F.  Emmons,  "Fluorspar  Deposits  of  Southern  Illinois,"  Tran^. 
Amer.  Inst.  Min.  Eng.,  February,  1892.  C.  J.  Norwood,  "Report  on  the 
Lead  Region  of  Livingston,  Crittenden  and  Qaldwell  Counties,"  Ken- 
tucky Geol.  Survey,  1875,  New  Series,  Vol.  I.,  p  449. 


240  KEMP'S  ORE  DEPOSITS. 

2.06.06.  Example  25.  Southwest  Missouri.  Zincbleude 
and  very  subordinate  galena  with  their  oxidized  products,  asso- 
ciated with  chert,  residual  clay,  calcite,  a  little  pyrite  and  bitu- 
men, in  cavities  of  irregular  shape  and  in  shattered  portions  of 
Subcarboniferous  limestone.  Across  Missouri,  from  a  point 
south  of  St.  Louis,  and  including  the  country  as  far  to  the 
northwest  as  Sedalia  and  Glasgow,  a  broad  belt,  called  the 
Ozark  uplift,  extends  southwesterly  into  Arkansas.  It  has 
formed  a  great  plateau  in  central  and  southern  Missouri,  and 
consists  largely  of  Silurian  rocks.  These  have  a  fringe  of 
Devonian  on  the  edges  and  dip  under  the  Lower  Carboniferous. 
The  plateau  reaches  1,500  feet  above  the  sea  in  Wright  County, 
but  on  the  limit  is  succeeded  by  lower  country.  To  the 
southwest  it  drops  somewhat,  with  Lower  Carboniferous  strata 
outcropping,  which  in  Kansas  are  overlain  by  the  coal  measures. 
The  surface  then  rises  again  in  the  prairies.  At  the  edge  of 
the  plateau  is  a  trough,  in  whose  bottom  the  Lower  Carbonifer- 
ous strata  are  cut  by  the  Spring  River,  which  flows  southwest- 
erly from  Missouri  across  the  western  State  line  into  Kansas, 
and  has  a  general  direction  parallel  to  the  western  limits  of  the 
uplift.  It  receives  tributary  streams  on  each  bank,  which  cut 
the  strata  in  strongly  marked  valleys,  and  afford  good  expo- 
sures. Those  on  the  east  bank,  from  south  to  north,  are  Shoal 
Creek,  Short  Creek,  Turkey  Creek  and  Center  Creek,  while 
from  the  west  come  the  Brush,  Shawnee,  and  Cow  creeks,  all 
in  Kansas.  Along  the  first  mentioned  creeks  the  principal 
mining  towns  are  situated,  but  others  are  found  on  the  minor 
streams.  They  extend  through  an  area  fifteen  miles  broad 
from  east  to  west,  and  twenty-five  miles  from  north  to  south. 
Newton  and  Jasper  are  the  most  productive  counties  in  Mis- 
souri, while  Cherokee  County,  in  Kansas,  also  contains  nota- 
ble mines.  Undeveloped  districts  are  recorded  in  Arkansas, 
but  apparently  at  a  lower  geological  horizon.  The  ore  occurs  in 
the  Keokuk  or  Archimedes  limestone  of  the  Lower  Carbonif- 
erous. A  generalized  section  of  the  rocks,  according  to  F.  L. 
Clerc,  is  as  follows :  On  the  higher  prairie,  some  15  feet  of 
clay  or  gravel;  10  feet  of  flint  or  chert  beds;  40  feet  of  lime- 
stone with  thin  beds  of  chert;  60  feet  of  alternating  layers  of 
limestone  and  chert;  100  feet  and  more  of  chert,  sometimes 
chalky  with  occasional  beds  of  limestone;  225  feet  in  total.     In 


LEAD  AND  ZINC. 


241 


basiDS  and  extensive  pockets  in  these  rooks,  deposits  of  slates 
with  small  coal  seams  are  found,  of  undetermined  geological 
relations.  The  large  bed  of  limestone  of  the  section  affords  a 
datum  of  reference  in  relation  to  which  the  ores  xm.y  be  de- 


P. 

% 

} 

•0 

% 

: 

S 

i 

c 

a 

1 

§ 

3%Found  Ore  . 

f^ 

f 

8%       "         " 

75% Found  40  to  80  ft.LeaQ  & 


No  Ore 


No  Pro 


CO"/$Found  Ore 


No  Ore 


60<!6Found  Zinc  On  at  1075  to  tlOO  ft. 


No  Ore 


The  Flint  and  Limestone  aameos  at  the  surface. 


Fig.  78. — Chart  shomng  the  results  of  deep  borings  in  the  Joplin  district,  Mo. 
From  the  Engineering  and  Mining  Journal,  March  18.  1899,  p.  321. 


scribed.  A  few  minor,  shallow  deposits  occur  in  the  flints  over 
it.  In  the  limestone  the  ores  are  associated  with  a  gangue  of 
dolomitic  clay  and  residual  flint.  They  occupy  irregular  cavi- 
ties or  openings,  locally  known  as  circles,  spar  openings,  and 


242  KEMP'S  ORE  DEPOSITS. 

ruDS.  (Clerc.)  Below  the  limestone  the  ore  is  found  in 
"sheets,  bands,  seams,  and  pockets,"  and  filling  in  the  inter- 
stices of  a  breccia  of  chert,  which  has  been  formed  by  the 
breaking  down  of  the  chert  layers  on  the  solutions  and  removal 
of  the  inter  bedded  limestones.  There  are  districts  where  the 
overlying  bed  of  limestone  has  also  disappeared,  and  they  then 
lack  it  for  a  capping.  The  deposits  extend  to  considerable 
depths  below  the  position  of  the  limestone.  The  present  mines 
have  not  demonstrated  as  yet  their  limit  of  depth.  At  times 
the  ore  is  associated  with  a  later-formed  quartz  rock  that  has 
coated  and  filled  the  cavities  of  the  breccia. 

Although  the  mining  is,  as  yet,  comparatively  shallow,  the 
results  of  a  large  number  of  deep  bore-holes  are  now  available, 
and  are  shown  in  the  accompanying  Fig;  78.  From  the  chart 
it  is  evident  that  there  are  four  ore- bearing  horizons  distributed 
down  to  a  depth  of  about  1,100  feet.  Below  this,  and  down  to 
2,005  feet,  no  ore  was  met.  The  holes  were  all  drilled  in  Jas- 
per County,  and  near  Joplin  and  Webb  City. 

2.06.07.  The  removal  of  the  interbedded  layers  of  limestone 
and  the  caving  in  of  the  associated  cherts  have  been  the  princi- 
pal causes  of  the  formation  of  cavities.  Adolph  Schmidt  re- 
ferred the  shrinkage  to  the  dolomitization  of  pure  lime  carbon- 
ate, an  idea  that  has  had  extended  adoption.  Dolomitization 
has  also  an  important  part  in  causing  the  general  porosity. 
Schmidt  traced  five  periods  in  the  geological  history  of  the  ore 
bodies:  1.  Period  of  deposition  of  the  rocks.  2.  Period  of 
dolomitization  of  certain  strata  and  of  principal  ore  deposition. 

3.  Period  of  dissolution  of  part  of  the  limestone,  of  breaking 
down  of  chert,  and  of  continued  but  diminishing  ore  deposition. 

4.  Period  of  regeneration,  secondary  deposition  of  carbonate  of 
lime  and  quartz,  and  continued  ore  deposition.  5.  Period  of 
oxidation. 

Schmidt's  work  was  done  in  1871-72.  Since  then  the  in- 
creased development  of  the  mines  has  afforded  greater  opportu- 
nities for  observation.  Haworth,  in  1884,  referred,  with  much 
reason,  the  shattering  of  the  chert  in  certain  areas  to  oscilla- 
tions of  the  strata,  and  Clerc,  in  1887,  emphasized  particularly 
the  dissolving  action  of  water.  It  is  a  hard  problem  to  dis- 
cover the  original  source  of  the  metals.  The  earlier  writers 
said  nothing  of  this  subject,  or  else,  as  in  Haworth's  paper,  dis- 


LEAD  AND  ZINC. 


243 


cussed  a  possible  precipitation  from  the  ocean,  or,  as  in  Clerc'^, 
referred  them  to  the  pockets  of  slate  and  coal.  In  1893,  at  the 
Chicago  meeting  of  the  American  Institute  of  Mining  Engi- 
neers, W.  P.  Jenney  presented  an  abstract  of  the  results  of  his 
work  while  detailed  by  the  U.  S.  Geological  Survey  to  study 
these  ore  deposits-  As  will  appear  in  the  abstract  of  the  paper 
given  below,  the  ores  are  supposed  to  have  come  up  through 
fissures  of  displacement,  and  hence  from  below.     These  con- 


/O^ 


Fig.  2. 


Typical  zinc-blende  ore-body  near  Webb  City,  Mo.   Vertical  Section 
•^ ^ubcarboniferous  Limestone 


Probable  flint  floor  of 
ore>deposit. 


•p^*^*'  Flint  rocK 


"^^^inc'blende  ore-bodie» 
rf-i^ -it    &  Flint  rock 


Worked  out  part  of 
ore-deposit. 


-^   -f — ^te-   Galenite  ia  fissures  &  bedding-planes  injlmestone 


Fig.  79. — Vertical  section  of  a  typical  zincUende  ore  body,  near  Webb  City, 
Mo.     After  C.  Henrich,  Irans.  Amer.  Inst.  Min.  Eng.,  XX.,  p.  14. 


elusions  have  been  controverted  by  others,  on  account  of  the 
difficulty  in  proving  the  existence  of  fauJts  when  evidence  of 
displacement  is  so  obscure.  In  Jenney's  paper  all  the  lead  or 
lead  and  zinc  regions  of  the  Mississippi  Valley  are  considered 
together.  They  are  described  as  occurring  along  three  lines 
of  upheaval.  The  region  of  Wisconsin  and  Iowa  is  on  the 
flanks  of  the  Archean  "Wisconsin  Island"  of  Chamberlin,  re- 
ferred to  above  under  2.00.01.     The  southeast  and  southwest 


244  KEMP'S  ORE  DEPOSITS. 

Missouri  regions  are  on  the  Ozark  uplift,  while  a  minor  argen- 
tiferous galena  district  is  on  the  line  of  the  Ouachita  uplift  of 
Arkansas  and  Indian  Territory.  The  formation  of  the  ore  bod- 
ies  in  the  first  three  of  these  is  regarded  as  having  been  in  gen- 
eral the  same.  They  are  thought  to  have  originated  from  up- 
rising solutions,  which  came  through  certain  principal  fissures, 
and  spread  laterally  into  strata  favorable  to  precipitation.  In 
southwest  Missouri  this  was  the  Cherokee  limestone  of  the 
Lower  Carboniferous.  In  its  unaltered  state  it  is  an  extremely 
pure  carbonate  of  lime.  It  has  a  maximum  thickness,  where 
not  eroded,  of  165  to  200  feet,  and  contains  many  interbedded 
layers  of  chert.  Much  organic  matter,  and  more  or  less  bitu- 
men, are  also  at  times  present.  The  limestone  seems  to  have 
been  raised  above  the  ocean  level  at  the  close  of  the  Lower 
Carboniferous,  and  to  have  remained  for  a  long  period  exposed 
to  the  atmospheric  agents.  Much  caving  in  of  unsupported 
layers  of  chert  and  much  attendant  brecciation  resulted.  The 
general  stratum  became  quite  open  and  cellular  in  certain 
portions.  At  a  later  period,  supposed  from  several  indications 
to  be  at  the  close  of  the  Cretaceous,  dynamic  disturbance  oc- 
curred, which  along  certain  lines  produced  fissures,  sometimes 
parallel,  sometimes  intersecting.  Solutions  arose  through  these 
which  dolomitized  much  of  the  remaining  limestone  and  caused 
additional  porosity.  Zinc  and  lead  ores  were  afforded,  and 
where  the  conditions  were  favorable  they  spread  laterally  from 
the  fissures  and  deposited  the  sulphides  in  the  cellular  rock  or 
replaced  the  limestone  itself.  The  intersection  of  crossing  fis- 
sures is  a  frequent  point  of  deposition,  and  at  times  parallel 
master  fissures  have  given  a  wide  area  of  impregnation.  This 
form  of  ore  deposit  is  called  a  run.  The  runs  are  from  5  to  50 
feet  in  height,  100  to  300  feet  long,  and  10  to  50  feet  across. 
At  Webb  City  ih^y  are  even  larger.  As  a  general  thing  the 
ore  is  in  the  interstices  of  the  brecciated  chert,  but  it  is  also  in 
limestone  and  dolomite,  and  associated  with  a  silicified  form  of 
the  insoluble  residue  left  bj^  the  solution  of  the  limestone, 
which  Jenney  calls  "cherokite."  All  the  ores  require  con- 
centration. Galena  usually  occurs  near  the  surface,  while 
blende  is  more  abundant  in  depth.  Cadmium  is  at  times  pres- 
ent in  the  blende  in  notable  amount. 
In  1894,  the  verj'  thorough  report  of  Arthur  Winslow  on  lead 


LEAD  AND  ZING.  245 

and  zinc  in  Missouri,  and  incidentally  elsewhere  in  the  world, 
appeared,  and  likewise  a  briefer  account  before  the  American 
Institute  of  Mining  Engineers.  Winslow  gives  in  the  large 
volumes  the  most  detailed  work  of  reference  yet  issued,  and 
reaches  a  quite  different  view  regarding  the  derivation  and  for- 
mation of  the  ores.  He  emphasizes  the  fact  that  the  region  has 
long  been  a  land  area,  in  fact,  ever  since  the  close  of  the  Lower 
Carboniferous  times.  The  subaerial  decay  has  therefore  been 
excessive  and  a  considerable  thickness  of  overlying  rock  has 
gone.  This  has  favored  the  formation  of  caves,  sinks  and  un- 
derground waterways,  which  have  often  collapsed.  Extremely 
careful  analyses  of  fresh  and  large  samples  of  the  various  lime- 
stones associated  with  or  overlying  the  lead  and  zinc  deposits 
of  the  State  were  made,  as  well  as  of  a  series  of  the  Archean 
rocks,  from  which,  in  the  course  of  long  erosion,  the  others 
are  supposed  to  have  been  derived.  The  Archean  rocks  yielded 
0.00197  to  0.0068  per  cent,  lead  (.04  to  .136  pounds  per  ton), 
and  0.00139  to  0.0176  per  cent,  zinc  (.028  to  .352  pounds  per 
ton);  the  Silurian  Magnesian  limestones,  a  trace  to  0.00156  per 
cent,  lead  (up  to  .03  pounds  per  ton);  and  a  trace  to  .0.01538 
per  cent,  zinc  (up  to  .307  pounds  per  ton);  the  Lower  Carbon- 
iferous limestones,  a  trace  to  0.00346  per  cent,  lead  (up  to  .07 
pounds  per  ton),  and  a  trace  to  0.00256  per  cent,  zinc  (up  to 
.05  pounds  per  ton).  Winslow  concludes  from  the  above  data 
and  observations  and  from  the  difficulty,  if  not  impossibility, 
of  discovering  actual  evidence  of  fault  fissures,  that  the  ores 
have  become  concentrated  in  the  shattered  rock  by  the  down- 
ward percolations  of  lead  and  zinc- bearing  solutions,  which 
have  derived  the  metals  from  the  overlying  and  largely  decom- 
posed strata. 

2.06.08.  Some  interesting  alterations  of  the  minerals  have 
occurred,  which  have  changed  the  blende  to  smithsonite  and 
calamine.  In  one  case  a  secondar}'  precipitation  of  zinc  sul- 
phide has  yielded  a  white,  amorphous  powder,  which  is  of  very 
recent  date.  With  the  original  precipitation  of  the  blende,  the 
asphaltic  material  may  have  had  something  to  do.  In  the 
matter  of  production,  W.  P.  Jenney  fixes  the  ratios  of  the 
blende,  galena,  and  pyrite  at  about  1,000  :  80  :  O.5.* 

^  Missouri. -t-G.  C.  Broadhead,  "Geological  History  of  the  Ozark  Up- 
lift," Amer.  GeoL,  III.,  6.     H.  M.  Chance,   "The  Rush  Creek  (Arkansas) 


246 


KEMRS  ORE  DEPOSITS. 


2.06.09.  Other  zinc  and  lead  deposits  are  known  in  central 
Missouri  generally  resembling  the  above  quite  strongly,  but 
of  less  economic  importance.  Some,  however,  are  described 
by  Schmidt  as  conical  stockworks.  They  sometimes  are  found 
in  Lower  Silurian  strata. 


ENLARGED   SECTION    SHOWING    RELATION    OF   ZINC-ORE 
TO   THE  -LIMESTONES   AND    CLAY. 


Fig.  80. — Oeological  section  of  the  Bertha  zinc  mines,  Wythe  County,  Va. 
After  W.  H.  Cas!\  Trans.  Amer.  Inst.  Min.   Eng.,  XXII. ,  p.  520. 

2.06.10.     Both  the  mines  of  Example  25  and  those  of  Exam- 
ple 24  were  originally  worked  for  lead,  and  the  zinc  minerals 

Zinc  District,"  !r?'a)is.  Amer.  Inst.  Min.  Eng.,  Yo\.  XVIII.,  p.  505,  1890. 
F.  L.  Clerc,  Geological  description  of  the  mines  in  a  statistical  pamphlet 
on  the  Lead  and  Zinc  Ores  of  Southwest  Missouri  Mines,  p.  4,  published 
by  J.  M.  Wilson,  Carthage,  Mo.,  1887.  Rec.  See  also  Eng.  and  Min. 
Jour.,  June  4, 1887,  p.  397;  "Zinc  in  the  United  States,"  Mineral  Resources, 
1882,  p.  368.  G.  T.  Cooley,  "Dressing  Lead  and  Zinc  Ores  in  Kansas," 
Eng.  and  Min.  Jour.,  July  7,  1895,  p.  9.  Eng.  and  Min.  Jour.,  November 
8.  188'^,  p.  380;  March  8,  1890.  p.  286.  "  Distribution  of  Lead  and  Zinc  near 
Joplin,  Mo.,"  Idem,  March  18,  1891,  321.  Rec.  E.  Haworth,  "  A  Contribu- 
tion to  the  Geology  of  the  Lead  and  Zinc  Mining  District  of  Cherokee 
County,  Kansas,  Oskaloosa.  Iowa."  1884  C.  Henrich,  "  Zincblende  Mines 
and  Mining  near  Webb  City,  Mo.,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXI., 
p.  3,  1892;  Eng.  and  Min.  Jour.,  June  4,  1892.  J.  R.  Hohbaugh,  "The 
Lead  and  Zinc  Mining  Industry  of  Southwest  Missouri  and  Southeast  Kan 
sas."  Eng.  and  Min.  Jour..  LVIIL,  1894,  199,  394,  413.  437,  460,  485.  508  and 
535.  Also  issued  as  a  separate  book  by  the  Scientific  Publishing  Co  .  50 
cents.  W.  P.  Jenney.  "Lead  and  Zinc  Deposits  of  the  Mississippi  Valley," 
Trans.  Amer.  Inst.  Min.  Eng.,  XXII.,  171,  1893.     Rec.     C.  Luedekingand 


LEAD  AND  ZING.  247 

were  regarded  as  a  nuisance ;  of  late  years  the  zinc  has  been 
much  more  of  an  object  than  the  lead.  The  deposits  in  south- 
west Virginia  (Example  26)  also  produce  lead,  but  are  best 
known  for  zinc. 

2.06.11.  Example  26.  Wythe  County,  Va.  Residual  de- 
posits or  crusts  of  calamine  and  smithsonite,  resting  upon 
Lower  Silurian  (Ordovician)  limestone  or  dolomite,  and  prob- 
ably derived  from  disseminated  blende,  during  the  weathering 
of  the  country  rock.  Deposits  of  blende  are  also  known  in  the 
limestone.  The  ore- bearing  terrane  is  exposed  over  a  considera- 
ble extent  of  country,  running  from  near  Roanoke,  one  hundred 
miles  westward.  The  largest  mines  are  in  Wythe  County,  and 
of  these  the  Bertha  is  best  known.     The  Bertha  ores  are  cala- 

H.  A.  Wheeler,  "Notes  on  Missouri  Barite,'  Amer.  Jour.  Sci.,  December, 
1891,  p.  495.  R.  W.  Raymond,  "Note  on  the  Zinc  Deposits  of  Southern 
Missouri,"  Trans  Airier,  hist.  Min.  Eng.,  VIII.,  165;  Eng.  and  Min.  Jour., 
October  4,  1879.  J.  D.  Robertson,  "  A  New  Variety  of  Zinc  Sulphide  from 
Cherokee  County,  Kansas,"  Amer.  Jour.  Sci.,  iii.,  XL.,  p.  160.  "Missouri 
Lead  and  Zinc  Deposits,"  Amer.  GeoL,  April,  1895,  235.  A.  Schmidt  and 
A.  Leonhard,  Missouri  Geol.  Survey,  1874.  A.  Schmidt,  "Forms  and 
Origin  of  the  Lead  and  Zinc  Deposits  of  Southwest  Missouri,"  Trans.  St. 
Louis  Acad.  Sci.,  III.,  246;  Amer.  Jour.  Sci.,  iii.,  X.,  p.  300.  Die  Bleiund 
Zink  Erzlagerstdtten  von  SiXdwest  Missouri,  Heidelberg,  Germany,  1876. 
E.  J.  Schmitz,  "Notes  of  a  Reconnaissance  from  Springfield,  Mo.,  into 
Arkansas,"  Trans.  Ainer.  Inst.  Min.  Eng.,  February,  1898.  W.  H.  Sea- 
mon,  "Zinciferous  Clays  of  Southwest  Missouri,"  Amer.  Jour.  Sci.,  ill., 
XXXIX.,  p.  38.  H.  S.  Wicks,  "The  Joplin  District,"  Engineering  Mag- 
azine, February,  1894.  Arthur  Winslow,  "  Notes  on  the  Lead  and  Zinc 
Deposits  of  the  Mississippi  Valley  and  the  Origin  of  the  Ores,"  Jour,  of 
Geol.,  I.,  612,  1893.  Rec.  "Lead  and  Zinc  Deposits  of  Missouri, "  Trans. 
Amer.  Inst.  Min.  Eng.,  XXIV.,  634  and  931.  Rec.  "Report  on  Lead  and 
Zinc,"  Missouri  Geol.  Survey,  VI.  and  VII.,  1894.  Rec.  See  also  pamphlet 
on  "Missouri  at  the  World's  Fair,"  1893.  "Historical  Sketch  of  Lead  and 
Zinc,"  Eng.  and  Min.  Jour.,  November  17,  24,  1894;  January  19,  1895. 

Kansas. — G.  P.  Grimsley,  "Kansas  Mineral  Products, "  Eleventh  Bien- 
nial Report  Kansas  Board  of  Agricidture,  1897-98,  502,  E.  Haworth,  "A 
Contribution  to  the  Geology  of  the  Lead  and  Zinc  Mining  District  of 
Cherokee  County,  Kan.,  Oskaloosa,  la.,"  1894,  privately  printed.  R.  Hay, 
' '  Geological  and  Mineral  Resources  of  Kansas, "  Eighth  Biennial  Report 
State  Board  of  Agriculture,  1891-92,  25.  B.  F.  Mudge,  Idem,  1878.  O. 
St.  John,  Idem,  1881-82.     See  also  J.  D.  Robertson,  cited  under  Missouri. 

Arkansas. — E.  J.  Schmitz,  "Notes  of  a  Reconnaissance  from  Spring- 
field,- Mo.,  into  Arkansas,"  Titans.  Amer.  Inst.  Min.  Eng.,  February,  1898. 
A  Report  on  Lead  and  Zinc  in  Arkansas  is  now  in  press  with  the  State 
Geol.  Survey  (1899). 


248 


KEMP  S  ORE  DEPOSITS. 


mioe  and  smithsoDite,  both 
crystallized  and  earthy  or 
ochreous.  They  lie  upon 
a  limestone  which  is  of 
very  irregular  surface,  be- 
ing so  deeply  pitted  by 
superficial  decay  that  it 
projects  in  knobs  and  pil- 
lars, and  sinks  in  interven- 
ing depressions.  These  are 
shown  very  graphically  in 
Figs.  82  and  83,  where 
they  are  left  in  relief  by 
the  stripping.  They  are 
mantled  and  rounded  off 
by  the  overlying  residual 
clay,  which  may  be  50  to 
?5  feet  deep.  The  ore  lies 
in  crusts  and  chunks  or  as 
a  powdery  mass  upon  or 
near  the  limestone  in  the 
clay,  and  is  won  either  by 
stripping  this,  or  by  shafts 
and  drifts.  (See  Fig.  80.) 
According  to  Boyd,  in  one 
section  there  are  486  feet 
of  strata  impregnated  with 
zinc  and  lead  sulphides, 
with  some  pyrite.  At  the 
Wythe  Company's  mines 
both  the  oxidized  ores  and 
the  unchanged  sulphides 
of  zinc  and  lead  in  the 
imderlying  limestone  are 
exploited,  but  at  the  Ber- 
tha mines  there  is  practi- 
cally no  lead,  the  product 
being  a  very  pure  spelter. 
More  or   less   limonite    is 


NiviNnownivd  oNiavoH 


esNiMONiz  vHxuaa 


•AM  '0  'H     'M  •«  'M  V  "M 
tl3AliiM3N 


AavtyAnawiM 


NlVJLNnOH  uadvuo 


n«»M 


>>  >::iss  7^< 


"i^-s  S2  §^  il 


oo)OorN.<oio-*miN  ^ 


5^ 


•aNIM-IVOO  VNOOXIV 


Fig.  82. — View  of  open  cut  in  the  Bertha  Zinc  Mines,  Va. 
photograph  by  J.  F.  Kemp,  1895. 


From  a 


Fig.  m.—View  of  open  cut  in  the  Wythe  Zinc  Mines,  Va. 
photograph  by  J.  F.  Kemp,  1895. 


From  a 


LEAD  AND  ZING.  249 

obtained  from  all  these  surface  workings,  and  is  sent  to  neigh- 
boring blast  furnaces. 

Near  Bonsacks  the  gossan  of  the  ore  was  exposed,  but  not 
recognized  for  a  long  time,  in  a  cut  of  the  Norfolk  and  Western 
R.  R.  The  mine  yielded  rich  earthy  oxidized  ores,  which,  how- 
ever, passed  in  depth  into  a  very  intimate  and  rebellious  mix- 
ture of  zinc-blende  and  pyrite.  These  deposits  extend  over  a 
wide  stretch  of  country,  running  from  near  Roanoke,  one 
hundred  miles  westward/ 

Related  deposits  occur  in  eastern  Tennessee,  and  have  fur- 
nished more  or  less  ore,  chiefly  calamine.  They  are  not  large 
as  a  rule.^  They  occur  in  the  Knox  dolomite,  at  the  base  of 
the  Lower  Silurian,  and  favor  its  contact  with  the  underlying 
Cambrian  Conasauga  shale^  in  the  area  of  the  Cleveland  folio 
cited  below. 

2.06.12.  Blende  is  a  frequent  associate  of  galena  in  the 
Rocky  Mountains,  but  it  has  been  only  recently  worked  for 
any  zinc  product,  and  then  largely  as  a  by-product  in  extract- 
ing silver.     (See  2.07.10.) 

*  C.  R.  Boyd,  "Resources  of  Southwest  Virginia,"  p.  71.  "Mineral 
Wealth  of  Southwest  Virginia,"  Trans.  Amer.  Inst.  Min.  Eng.,  V.,  81; 
Ibid.,  VIII.,  340.  "  The  V^ythe  Lead  and  Zinc  Mines,  Va.,"  E7ig.  and  Min. 
Jour.,  June  17  and  24,  1893.  W.  H.  Case,  "The  Bertha  Zinc  Mines  at 
Bertha,  Va.,"  Trans.  Amer.  Inst.  Min.  Eng.,  Vol.  XXII.,  p.  511,  August, 
1893.  H.  Credner,  Zeitsch.  fur  die  gesammten  Naturwissenschaften,  1870, 
XXXIV.,  p.  24.  F.  P.  Dewey,  "Note  on  the  Falling  Cliff  Zinc  Mine 
(Bertha  Company),"  Trans.  Amer.  Inst.  Min.  Eng.,  X.,  111.  A.  v. 
Groddeck,  Typus  Austin.  Lehre  von  den  Lagerstdtten  der  Erze,  p.  103. 

'  J.  M.  Safford,  Geology  of  Tennessee,  p.  482.  W.  H.  Gildersleeve, 
"Zinc  Ores  in  Tennessee,"  University  Scientific  Magazine,  August,  1896. 
Quoted  by  the  Eng.  and  Min.  Jour.,  September  18,  1897,  336. 

^  Cleveland  Folio,  by  C.  W.  Hayes.  U.  S.  Geol.  Survey,  Morristown 
Folio.    Arthur  Keith,  Idem, 


CHAPTER  VII. 

ZINC  ALONE,  OR  WITH  METALS  OTHER  THAN  LEAD. 

2.07.01.  Zinc  commonly  occurs  in  association  with  lead, 
but  there  are  one  or  two  exceptional  deposits  in  this  country 
which  are  without  lead,  and  which  have  no  parallel  in  other 
parts  of  the  world.  The  minerals  containing  zinc  at  Franklin 
Furnace  and  Ogdensburg,  N.  J.,  are  known  elsewhere  only  as 
rarities,  although  they  are  found  in  vast  amounts  in  New 
Jersey.^ 

ZINC   SERIES. 

Zn.  S.        Fe.      SiO^.     Mn. 

Sphalerite  (commonly  call  blende)  ZnS 67        33     

Zincite,  ZnO 80.3     ,. 

Franklinite,  (Fe.Zn.Mn)0(Fe.Mn)203  (variable)    5.54..     51.8     

Willemite,  2ZnO.Si02 58.5     27.0 

Calamine,  2ZnO.SiO 2,  H^O 54.3     ..     25.0 

Smithsonite,  ZnO.COg 52.0     

2.07.02.  Example  27.  Saucon  Valley,  Pennsylvania. 
Zinc-blende  and  its  oxidation  products,  calamine  and  smith- 
sonite,  filling  innumerable  cracks  and  fissures  in  a  disturbed, 
magnesian  limestone,  thought  to  belong  to  the  Chazy  stage. 
The  ore  bodies  occur  in  the  Saucon  Valley  near  the  town  of 
Friedensville,  about  four  miles  south  of  Bethlehem.  The  lime- 
stone is  inclosed  between  two  northerly  spurs  of  the  South 
Mountain,  and  has  apparently  been  tilted  and  shattered  by 
the  upheaval  of  the  latter.  The  shattering  and  disturbances 
decrease  as  the  South  Mountain  is  left  and  the  dip  decreases. 
There  are  three  principal  mines,  the  Ueberroth,  the  Hartman, 
and  the  Saucon,  the  first  named  being  in  the  portion  which  is 

^  F.  L.  Clerc,  "Zinc  in  the  United  States,"  Mineral  Resources,  1882,  p. 
358.  W.  R.  Ingalls,  "  The  Nomenclature  of  Zinc  Ores,"  Trans.  Amer.  Inst. 
Min,  Eng.,  XXV.,  17  and  955,  1895. 


ZINC  ALONE.  251 

tilted  nearly  to  a  vertical  dip,  and  is  much  disturbed,  while 
the  next  is  where  the  dip  has  gradually  decreased  to  35°.  The 
mines  are  on  a  belt  some  three-quarters  of  a  mile  long.  At  the 
Ueberroth  an  enormous  quantity  of  calamine  was  found  on  the 
surface,  but  it  passed  in  depth  into  blende  and  was  clearly  an 
oxidation  product.  In  the  others  the  blende  came  nearer  the 
surface.  The  ore  follows  the  bedding  planes,  and  the  joints 
normal  to  these  throughout  a  zone  varying  from  10  to  40  feet 
across,  and  fills  the  cracks.  At  their  intersection  the  largest 
masses  are  found.  Six  larger  parallel  fissures  were  especially 
marked  at  the  Ueberroth.  This  mine  proved  in  development 
to  be  very  wet,  and  a  famous  pumping  engine,  the^  largest  of 
its  day,  was  built  to  keep  it  dry.  The  Hartman  and  Saucon 
are  less  wet.  A  little  pyrite  occurs  with  the  blende,  and  thin, 
powdery  coatings  of  greenockite  sometimes  appear  on  its  sur- 
face, but  it  is  entirely  free  from  lead  and  a  very  high  grade  of 
spelter  is  made  from  it.  The  mines  were  strong  producers 
from  1853  to  1876,  but  little  has  been  done  since,  although  it  has 
been  reported  that  the  great  pumping  engine  might  again  start, 
and  the  mines  may  once  more  furnish  considerable  quantities  of 
ore. 

2.07.03.  The  v^ins  were  evidently  filled  by  circulations  from 
below  that  brought  the  zinc  ore  to  its  present  resting  place  in 
the  shattered  and  broken  belt.  Drinker  considers  it  to  have 
been  derived  from  a  disseminated  condition  in  the  limestone.^ 

2.07.04.  Example  28.  Franklin  Furnace  and  Sterling, 
N.  J.  Bed  veins  consisting  of  franklinite,  willemite,  zincite, 
etc.,  in  crystalline  limestone,  in  many  respects  analogous  to  the 
magnetite  of  Example  13.  The  franklinite  and  zincite  bedded 
deposits  are  in  a  belt  of  white,  crystalline  limestone  which  runs 
southwesterly  from  Orange  County,  New  York,  across  north- 
western New  Jersey.  It  was  considered  metamorphosed  Lower 
Silurian  by  H.  D.  Rogers,  but  its  association  with  Archean 
gneiss  is  so  intimate  and  involved  that  others  have  regarded  it 
as  likewise   Archean.     Blue   Siluro-Cambrian   limestone   and 

'  F.  L.  Clerc,  Mineral  Resources,  1882,  361.  Rec.  H.  S.  Drinker,  "On 
the  Mines  and  Works  of  the  Lehigh  Zinc  Company,"  Trans.  Amer.  Inst. 
Min.  Eng.,  I.,  67.  C.  E.  Hall,  in  Rep.  D3,  Second  Geol.  Survey,  Penn.,  p. 
239.  Die  Gruben  und  Werke  der  Lehigh  Zink  Gesellschaft  in  Pennsyl 
vanien,  B.  und  H.  Zeit. ,  1872,  p.  51. 


252 


KEMP'S  ORE  DEPOSITS. 


quartziteare  also  near.  F.  L.  Nason  has  recently  supported  the 
Cambro-Silurian  age  of  the  'white  limestone,  on  the  ground 
that  the  white  and  the  blue  varieties  are  inextricably  involved, 
and  that  many  intrusions  of  granite  are  present,  which  would 
account  for  the  metamorphism  of  the  latter.  In  one  of  the 
smaller  areas  of  blue  that  was  in  the  midst  of  the  white,  some 
fossils  of  the  Olenellus  fauna  were  discovered.  J.  E.  Wolff 
and  others  in  association  with  him  have  referred  the  white 
limestone  to  the  Archean  rocks,  and  have  agreed  that  the  blue 
was  either  mixed  with  it  because  of  faults  or  because  the 
quartzite  had  filled  cavities  in  the  former  during  the  advance  of 
the  Cambrian  sediments  across  the  Archean  rocks.  Of  the 
presence,  however,  of  granites  and  other  intrusions  in  the  white 
limestone  there  is  no  doubt,  but  they  are  thought  by  Wolff  to 
be  pre- Cambrian,  and  probably  to  be  later  than  the  ore.  In 
limestones  and  ore  at  once  so  mashed  and  so  old  the  relations 


Fig.    84. — Ci^oss   section    at    Franklin    Furnace,    JV.    J.,    corresponding    to 

A  A.  of  map  (FiG.  88),  and  Jour  times  the  scale  of  map.      At  the  left 

is  blue  limestone  and  quartzite.     After  J.    F.   Kemp, 

Trans.  N.  Y.  Acad,  of  Sciences,  XII [.,  86,  1893. 

are  obscure.  At  Franklin  Furnace  the  crystalline  limestone 
forms  a  low  hill  (Mine  Hill)  east  of  the  upper  waters  of  the 
Wallkill,  and  again  at  Ogdensburg,  two  miles  south,  another 
(Sterling  Hill),  on  the  west  bank.  There  is  a  valley  and  unex- 
posed strip  between,  so  that  the  unbroken  continuity  without  a 
possible  intervening  fault  cannot  be  established.  The  bed  at 
Franklin  outcrops  on  the  west  side  of  the  hill.  It  begins  on 
the  north  just  across  the  Hamburg  road,  and  runs  south  30° 
west  as  a  continuous  bed  for  about  2,500  feet.  This  portion  is 
called  the  Front  vein.  It  contains  on  the  north  the  old  Ham- 
burg mine,  then  the  Trotter  mine,  and  in  the  southern  portion 
belongs  to  the  New  Jersey  Zinc  and  Iron  Company.  It  runs 
from  8  to  30  feet  broad  at  the  outcrop,  but  swells  below.  It 
dips  southeast  40  to  60°  into  the  hill,  and  is  interbedded  in  the 
jimestone.     In  the  Trotter  mine  a  wedge  or  horse  of  hornblende, 


Fig.  85. — View  of  the  west  vein  at  Franklin  Furnace  looking  south.     The 

two  shafts  are  at  the  Trotter  Mine.    Photographed 

by  J.  F.  Kemp,  1893. 


Fig.  S6.—Vieiv  of  open-cut  at  south  end  of  Jfine  Hill,  Franklin  Furnace, 

N.  J. ,  exposing  the  syncline  of  ore.     From  a  photograph 

hy  J.  F.  Kemp,  February  24.  1899. 


Fig.  87. — View  of  Stirling  Hill,  Ogdensburgh,  N.  J.,  looking  southwest  from 

the  N.  Y. ,  S.  and  W.  R.  R.  embankment.     The  mines  are  at  the 

foot  of  the  hill.     From  a  photograph  by 

J.  F.  Kemp,  1892. 


ZING  ALONE.  253 

augite,  plagioclase,  and  various  other  silicates  enters  the  bed  a 
short  distance.  In  this  horse  some  of  the  most  interesting 
minerals  have  been  found,  such  as  fluprite,  rhodonite,  blende 
(var.  cleiophane),  smaltite  (var.  cholanthite ),  axinite,  etc.  At 
the  end  of  the  Front  vein — or,  more  properly,  bed — a  branch  or 
bend  strikes  off  at  an  angle  of  30  to  40°  to  the  east.  This  more 
easterly  branch,  which  is  called  the  Buckwheat  mine,  outcrops 
on  the  surface  some  500  feet,  and  then,  after  being  cut  by  a 
trap  dike  22  feet  wide,  pitches  down  at  an  angle  of  27°  and 
passes  under  the  limestone.  The  portion  of  the  mine  northeast 
of  the  dike  furnishes  the  most  and  best  ore.  The  surface  out- 
crop of  the  Buckwheat  was  25  to  30  feet  across,  but  it  swelled 
below  to  52  feet,  and  in  the  second  level,  about  200  feet  from 
the  surface,  it  was  penetrated  by  a  cross-cut  125  feet  without 
finding  the  wall.  The  character  of  the  ore  varies;  for,  while 
it  is  excellent  at  the  point  of  the  cross-cut,  at  125  feet  nearer 
the  intersection  Avith  the  front  bed  it  becomes  lean,  while  pre- 
serving its  width  lower.  Beyond  the  dike  the  bed  is  likewise 
broad,  and  is  mined  out  for  40  to  50  feet  across.  The  workings 
are  now  some  distance  down  on  the  pitch.  The  impression 
made  by  the  arch  of  the  roof  and  by  the  curving  beds  is  that 
this  is  the  crest  of  an  anticline  whose  axis  pitches  north  27°, 
and  whose  central  portion  is  formed  by  the  franklinite  bed 
being  doubled  up  together  on  itself  before  the  two  parts  diverge 
in  depth.  Its  western  portion  probably  is  continuous  in  a  syncli- 
nal trough  with  the  front  bed,  and  its  eastern  portion  dips  east 
at  some  unknown  angle.  It  may,  however,  be  merely  a  bulg- 
ing termination  of  the  bed  and  the  results  of  deeper  mining  will 
be  awaited  with  interest. 

About  1890  deep  drilling  was  instituted  along  the  strike  of 
the  Buckwheat  or^,  and  about  one-third  of  a  mile  distant  from 
it.  The  holes  caught  the  ore  at  approximately  1,000  feet  down, 
and  a  large  shaft  was  at  once  installed  which  has  since  proved 
extremely  productive.  The  workings  have  shown  that  the 
prolongation  of  the  Buckwheat  ore  body  flattens  notably  at  this 
portion,  and  rounds  out  along  the  strike  in  a  sort  of  spoon-bowl 
termination.  To  express  the  exact  shape  in  this  portion  the 
stereogram  Fig.  90  should  he  somewhat  modified,  still  it  illus- 
trates the  general  shape  fairly  well.  Apparently  the  ore  is  cut 
off  by  a  fault  to  the  northeast,  but  the  relations  are  not  yet 


^54  KEMP'S  ORE  DEPOSITS. 

fully  demonstrated.  The  whole  southern  portion  of  the  ore 
body,  as  far  as  the  trap  dike,  is  now  being  stripped  of  limestone 
preparatory  to  open-cut  mining,  and  the  geological  relations 
are  beautifully  displayed. 

2.07.05.  The  ore  consists  of  franklinite  in  black  crystals, 
usually  rounded  and  irregular,  but  at  times  affording  a  quite 
perfect  octahedron  combined  with  the  rhombic  dodecahedron 
and  set  in  a  matrix  of  zincite,  willemite  and  calcite.  The  rich- 
est ore  lacks  the  calcite  and  consists  of  tho  other  three  in  vary- 
ing proportions.  The  best  ore  is  in  largest  amount  in  the 
Buckwheat  mine,  beyond  the  trap  dike  which  cuts  it.  The 
limestone  containing  the  ore  has  a  notable  percentage  of  man- 
ganese replacing  the  calcium,  and  where  it  is  exposed  to  the 
atmosphere  it  weathers  a  characteristic  brown.  An  analysis 
of  a  sample  occurring  with  the  ore  at  Sterling  Hill  afforded 
F.  C.  VanDyck: 

CaCOj 80.33 

MnCOg 16.57 

FegOg 0. 50 

SiOg 0.20 

HgO 1.00 

100.50 

The  percentage  of  manganese  is  very  high  for  a  limestone. 

2.07.06.  The  Sterling  Hill  outcrop  is  less  extensive.  It  be- 
gins on  the  north  with  the  New  Jersey  Zinc  and  Iron  Com- 
pany's propert}^  and  runs  south  30°  west  for  1,100  feet.  It 
then  branches  or  bends  around  to  the  west  and  runs  north  60° 
west  for  30  feet,  bending  again  to  north  30°  east,  and  pitches 
beneath  the  surface.  Thus  the  general  relations  between  the 
front  and  back  beds  are  somewhat  the  same  .as  at  Mine  Hill, 
and  the  dip  and  pitch  are  similar.  The  principal  workings 
are  on  the  Front  vein,  where  there  are  two  veins  (beds),  ac- 
cording to  the  older  descriptions,  one  rich  in  franklinite  and 
the  other  in  zincite.  It  is  doubtful  if  there  really  are  two  dis- 
tinct beds,  but  probably  one  portion  is  richer  in  zincite  than 
the  other.  The  part  mined  is  from  two  to  ten  feet.  The  foot- 
wall  is  corrugated  and  causes  many  pinches  and  swells,  whose 
troughs  pitch  north.  The  limestone  between  the  front  and 
back  outcrop  is  charged  with  franklinite  and  various   silicates 


ZING  ALONE. 


255 


(jeffersonite,  augite,  garnets,  etc.),  and  has  been  mined  out  in 
large  open  cuts  now  abandoned.  A  deposit  of  calamine  was 
found  in  the  interval  about  1876,  and  has  furnished  many  fine 
museum  specimens. 

2.07.07.  It  is  not  clear  that  the  Sterling  Hill  and  Mine  Hill 
deposits  were  once  continuous.  The  bed  at  Mine  Hill  runs  in 
the  front  portion  close  to  the  contact  of  the  white  limestone 
and  the  gneiss.  The  Sterling  Hill  bed  is  much  farther  awaj^ 
from  the  gneiss,  and  this  would  indicate  that  it  is  at  a  higher 
horizon.  The  evidence,  too,  of  a  pitching  syncline  is  strong, 
but  a  pitching  S-fold  is  not  as  clear.  A  faulting  of  the  Arche- 
an  rocks  in  an  east  and  west  line  across  their  strike,  and  a  sub- 
sequent tilting  so  as  to  give  them  a  northerly  pitch,  is  a  very 


Figures  88  and  89. — Geological  maps  of  Mine  Hill  and  Sterling  Rill, 

showing  the  relations  oj  the  ore-hodies.     After  J.   F.  Kemp, 

Trans.  N.    T.  Acad,  of  Sciences,   Kill., 

pp  81  and  85,  1893. 


widespread  phenomenon  in  the  Highlands,  and  lends  weight 
in  this  instance  to  the  idea  that  a  fault  intervenes  between  the 
two  hills. 

2.07.08.  The  origin  of  these  beds  is  very  obscure.  They 
are  so  unique  in  their  mineralogical  composition  that  very  lit- 
tle direct  aid  is  furnished  by  deposits  elsewhere.  At  Mine 
Hill,  below  the  franklinite  bed  a  bed  of  magnetite  was  early 
discovered,  and  was  mined  for  iron.  It  has  since  been  met  in 
the  drill  cores  from  the  deep  shaft  of  the  northeast,  and  is 
therefore  remarkably  persistent  beneath  the  zinc  ore.  There 
are  man}-  points  of  analogy  between  the  franklinite  beds  and 
extended  magnetite   deposits.     They  are   both   minerals  of  the 


256. 


KEMP'S  ORE  DEPOSITS. 


spinel  group,  and  the  spinels  are  a  common  result  of  raetamor- 
phic  action.  The  presence  of  zincite  and  willemite  complicates 
matters,  however,  and  while  an  original  ferruginous  deposit 
might  be  conceived  with  a  large  percentage  of  manganese, 
such  abundance  of  zinc  is  beyond  previous  experience.  It 
is,  however,  suggestive  that  no  inconsiderable  amount  of  zinc 
is  found  in  the  Low  Moor  (Va.)  limonites,  as  shown  by  the 
flue  dust  (see  E.  C.  Means,  *'The  Dust  of  the  Furnaces  at  Low 
Moor,  Va.,"  Buffalo  meeting,  Amer,  Inst.  Min.  Eng.,  XVII., 
p.  179),  and  this  in  the  course  of  a  protracted  blast  may  amount 
to  many  tons,  but  it  does  not  approach  the  Franklin  Furnace 
ores.  None  the  less,  in  the  absence  of  a  better  explanation,  the 
franklinite  bed  may  be  thought  of  as  perhaps  an  original  man- 


FlGURES  90  and  91. — Stereograms  of  the  ore  bodies  at  Mine  Hill  and 

Sterling  Hill.     After  J.   F.  Kemp,   Trans.  N.    Y.  Assoc. 

of  Sciences,  XIII. ,  pp.  83  and  89,  1893. 

ganese,  zinc,  iron  deposit  in  limestone,  much  as  many  Siluro- 
Cambrian  limonite  beds  are  seeii  to-day,  and  that  in  the  gen- 
eral metamorphism  of  the  region  it  became  changed  to  its  pres- 
ent condition.  Minerals  of  the  spinel  group  occur  all  through 
this  limestone  belt,  and  in  Orange  County,  New  York,  to  the 
north,  there  is  an  old  and  prolific  source  of  them. 

2.07.09.  As  has  been  earlier  stated,  granite  intrusions  are 
common  in  the  white  limestones  adjacent  to  or  near  the  ore, 
and  unless  these  are  proved  to  be  of  later  age  than  the  ore,  they 
may  have  been  an  important  factor  in  the  ore  formation.  It 
is  very  reasonable  that  the  igneous  intrusion  should  start  ore- 
bearing  currents  along  a  certain  stratum  in  the  limestone, 
which  would    replace  it   with    ore.     Subsequent  folding  and 


ZING  ALONE.  UH 

metamorph ism  must  then  have  changed  these  ores,  whatever 
they  were,  to  the  present  unusual  minerals. 

This  view  of  the  method  of  origin  has  been  advocated  by 
J.  F.  Kemp  in  the  paper  cited  below,  and  more  careful  search, 
as  well  as  the  sinking  of  the  new  shaft  on  the  strike  of  the 
back  vein  at  Mine  Hill,  have  served  to  bring  to  light  more 
intrusions  of  granite  than  were  previously  known.  Chon- 
drodite,  fluorite  and  other  contact  minerals  occur  near  them. 
Nason  has  also  shown  by  an  interesting  series  of  analyses  that 
the  limestone  next  the  granites  tends  to  be  pure  CaCOs,  shading 
gradually  at  a  distance  to  dolomitic  varieties.  Victor  Mon- 
heim,  in  discussing  the  vein  of  willemite  worked  in  the  forties 
at  Stolberg,  near  Aachen,  has  urged  that  at  temperatures  suffi- 
ciently high  the  anhydrous  silicate  of  zinc  may  separate  di- 
rectly from  the  solutions,  while  at  lower  temperatures  the 
hydrous  salt  results.  His  experiments  and  conclusions  give 
support  to  the  view  that  the  igneous,  plutonic  intrusions  have 
played  an  important  role  in  the  ore  deposition.  (See  V.  Mon- 
heim,  Verh.  d,  Naturhist  Ver.  der  preus.  Rheinlande  u. 
Westphalen,  V.,  162, 1848;  VI.,  1,  1849.)  Were  this  true  we 
would  not  be  compelled  to  assume  an  original  bed  of  blende 
from  which  these  oxidized  compounds  have  been  derived.  It 
is  a  general  experience,  however,  that  hydrated  oxidized  ores 
of  zinc  have  passed  in  depth  into  blende,  and  this  fact,  in  con-' 
nection  with  the  almost  entire  absence  of  blende  in  these  mines, 
adds  to  their  puzzling  character.  Were  they,  however,  at  one 
time  a  thoroughly  oxidized  gossan  containing  the  three  metals 
specially  prominent,  the  intrusions  of  granite  are  probably 
responsible  for  the  change  to  their  present  combinations.^ 

*  F.  Alger,  "On  the  Zinc  Mines  of  Franklin,  Sussex  Co.,  IT.  J.,"  Amer. 
Jour.  Sci.,  i.,  XLVIII.,  252,  1845.  Rec.  J.  Beco,  De  I'Etat  actual,  des 
Industries  du  Zinc,  etc.,  aux  Etats  Unis  dAmerique,  Revue  Universelle 
des  Mines,  1877,  II.,  129.  W.  P.  Blake,  in  paper  on  "Zinc  Ore  Deposits 
of  Southwestern  New  Mexico,'  Trans.  Amer.  Inst.  Min.  Eng.,  XXIV.,  187, 
1894,  gives  notes  on  the  "  New  Jersey  Ore  Bodies.'  N.  L.  Britton,  Ann. 
Hep.  of  the  State  Geologist,  N.  J.,  1886,  p.  89.  An  excellent  cross-section 
of  Mine  Hill  is  given.  G.  H.  Cook,  "  On  the  Probable  Age  of  the  White 
Limestone  at  the  Sussex  and  Franklin  Zinc  Mines,"  Amer.  Jour.  Sci.,  ii., 
XXXII.,  208.  Geol.  of  New  Jersey,  669,  1868,  with  map.  Rec.  H.  Cred- 
ner,  "On  the  Franklinite  Beds,"  .Bergrw.  HUtt.  Zeitung,  1866,  29;  1871, 
369.     Rec.     E.  F.  Dui-re,   "  Metallurgische  Notizen  aus  New  Jersey  und 


258  KEMP'S  ORE  DEPOSITS. 

2.07.10.  Blende  is  kDown  in  numerous  places  in  the  Rocky 
Mountains,  and  is  often  argentiferous.  When  mixed  with 
lead  silver  ores  it  has  generally  proved  a  drawback,  and  has 
raised  the  smelting  charges.  Recently  works  have  been  erected 
at  Canon  City,  Col.,  for  the  treatment  of  such  ores,  and  very 
considerable  quantities  of  blende  are  there  turned  into  zinc- 
white.  While  the  local  demand  for  this  pigment  is  not  so 
heavy  in  the  West  as  in  the  East,  any  process  which  frees  the 
dem  Lehigh  Thai,"  Zeitsch.  des  Vereins  deutscher  Ingenieure,  1894,  p.  184. 
B.  K.  Emerson,  ' '  On  the  Dykes  of  Micaceous  Diabase,  Penetrating  the 
Bed  of  Zinc  Ore  at  Franklin  Furnace,  Sussex  Co  ,  N.  J.,"  Amer.  Jour.  Set., 
May,  1882,  376.  Aug.  F.  Foerste,  "New  Fossil  Localities  in  the  Early 
Paleozoics  of  Pennsylvania,  New  Jersey  and  Vermont,"  etc.,  Amer.  Jour. 
Sci.,  iii.,  XLVI.,  345.  Discusses  the  local  stratigraphy  with  a  map.  P. 
Groth,  "Die  Zinkerzlagerstatten  von  New  Jevsej,"  Zeitschrift  fur  Prak- 
tische  Geologie,  May,  1894,  p.  230.  W.  H.  Keating  and  L.  Vanuxem, 
"Geology  and  Mineralogy  of  Franklin  in  Sussex  County,  N.  J.,"^ 
Jour.  Phila.  Acad.  Nat.  Sci.,  II.,  277,  1822.  Rec.  J.  F.  Kemp,  "The  Ore 
Deposits  at  Franklin  Furnace  and  Ogdensburgh,  N.  J.,"  Trans.  N.  Y. 
Acad.  Sci.,  XIII.,  76-98,  1893;  gives  a  full  bibliography  and  annotated  list 
of  minerals.  Rec.  F.  L.  Nason,  Ann.  Rep.  State  Geol.,  N.  J.,  1890,  p.  25; 
Amer.  Geol,  VIL,  241;  VIIL,  166;  XII.,  154.  Amer.  Jour.  Sci.,  in., 
XXXIX.,  407,  1890.  "The  Franklinite  Deposits  of  Mine  Hill,  Sussex 
County,  N.  J.,"  Trans.  Amer.  Inst.  Min.  Eng.,  February,  1894;  Eng.  and 
Min.  Jour.,  May  3,  1894,  p.  197.  Rec.  "Chemical  Composition  of  Some 
of  the  White  Limestone  in  Sussex  Co.,  N.  J.,"  Amer.  Geol.,  March,  1894, 
*p.  154.  T.  Nuttall,  "Geological  and  Mineralogical  Remarks  on  the  Min- 
erals of  Paterson  and  on  the  Valley  of  Sparta,"  iV.  Y.  Med.  and  Phys. 
Jaun,  April,  May  and  June,  1822.  Amer.  Jour.  Sci.,  i.,  V.,  239,  1822. 
Jos.  C.  Platt,  Jr.,  "The  Franklinite  and  Zinc  Litigation  Concerning  the 
Deposits  of  Mine  Hill  at  Franklin  Furnace,  Sussex  Co. ,  N.  J. ,"  Trans.  Amer. 
Inst.  Min.  Eng.,  V.,  580,  1876-77.  H.  D.  Rogers,  "Geology  of  New  Jer- 
sey, 1849,  pp.  63-71,  with  a  list  of  Minerals  by  Dr.  S.  Fowler."  Rec.  G.  C. 
Stone,  "Analyses  of  Franklinite  and  Some  Associated  Minerals  (two 
analyses  of  Zincite,  four  of  Franklinite,  five  of  Willemite,  one  of  Teph- 
roite),"  School  of  Mines  Quarterly,  VIII.,  148,  1887.  G.  Troost,  "Observa 
tions  on  the  Zinc  Ores  of  Franklin  and  Sterling,  Sussex  Co.,  N.  J.,"  Jour. 
Phil.  Acad.  Nat.  Sci.,  IV.,  220,  1824.  J.  P.  Wetherell,  "The  Mine  Hill 
Ore  Deposits  in  New  Jersey  and  the  Wetherell  Concentrating  Plant, "  Eng. 
and  Min.  Jour.,  July  17,  1897.  J.  D.  Whitney,  "Metallic  Wealth  of  the 
United  States,"  p.  348,  1854.  J.  E.  Wolff  and  A.  H.  Brooks,  "The  Age  of 
the  Franklin  White  Limestone  of  Sussex  Co.,  N.  J.,"  XVIII.,  Ann.  Rep. 
Dir.  U.  S.  Geol.  Survey,  Part  II.,  pp.  425-457,  1899.  J.  E.  Wolff,  "Oc- 
currence of  Native  Copper  at  Franklin  Furnace,  N.  J.,"  Proc.  Amer.  Acad. 
Arts  and  Sci.,  XXXIII.,  429,  1898.  " Hardy stonite,  a  new  Calcium- zinc 
Silicate  from  Franklin  Furnace,  N.  J.,"  Proc.  Amer.  Acad.  Arts  and  Sci., 
XXXIV.,'479. 


ZINC  ALONE.  259 

lead-silver  or  copper-silver  ores  of  the  objectionable  zinc 
will  operate  favorably  on  many  mines  now  handicapped.  This 
has  already  proved  to  be  the  case  with  the  refractor}^  sulphides 
met  in  depth  at  Leadville. 

Deposits  of  oxidized  ores  in  southwestern  New  Mexico,  near 
the  town  of  Hanover,  have  recently  been  mined  to  a  notable 
extent.  The  smithsonite  and  calamine  as  well  as  the  blende, 
which  is  met  in  the  same  vicinity,  are  unmixed  with  galena,  but 
the  blende  often  contains  intermingled  pyrites.  The  ores  occupy 
irregular  caverns  and  seams  in  Paleozoic  or  Archean  limestone, 
in  close  geological  association  with  intrusive  granite,  contact 
zones  and  iron  ores.  A  lenticular  shape  is  often  notable  in  the 
masses  of  blende.  As  remarked  by  Blake,  the  deposits  show 
some  interesting  points  of  resemblance  to  those  of  New  Jersey. 
The  richest  carbonates  and  calamine  have  been  shipped  to  the 
East,  but  with  the  unavoidably  high  freights  only  the  purest 
and  best  surface  ores  are  available.  (W.  P.  Blake,  *' Zinc-ore 
Deposits  of  Southwestern  New  Mexico,"  Trans.  Amer.  Inst, 
Min.  Eng.,  XXIV.,  187.)  Large  deposits  of  hematite  and  mag- 
netite have  been  worked  to  some  extent  in  the  same  region,  as 
a  flux  for  lead-silver  smelters,  but  their  remoteness  militates 
against  their  use  as  an  iron  ore. 

2.07.11.  A  large  amount  of  zinc  ore  is  turned  directly  into 
zinc  white  and  employed  as  a  pigment.  For  this  reason  the 
statistics  of  the  metal  do  not  indicate  all  the  ore  mined.  The 
accompanying  figures  are  short  tons.  For  detailed  statistics 
seethe  annual  volumes  on  "Mineral  Industry"  of  the  Engineer- 
ing and  Mining  Journal,  1894,  and  the  Annual  Reports  of 
the  U.  S.  Geological  Survey. 

1882.  ISiK).  1897. 

Illinois  and  Indiana 18,201  26,243  38,680 

Kansas 7,366  15,199  33,895 

Missouri 2,500  13,127  18,413 

Eastern  and  Southern  States 5, 698  9,114  9, 900 

33,765  63,683        100,387 

The  amounts  for  1882  and  1890  are  from  the  Mineral  Re- 
sources of  the  UniteU  States,  1889-90.  p.  89,  those  for  1897 
are  from  the  Mineral  Industry,  VI.,  H61.  The  statistics  give 
the  metallurgical  output  for  the  several  States,  not  the  mining. 
Indiana  has  no  zinc  mines. 


CHAPTER    VIII. 

LEAD  AND   SILVER. 

2.08.01.  There  are  two  general  methods  of  extracting  silver 
from  its  ores,  the  one  indirectly,  by  smelting  with  and  for  lead ; 
the  other  by  amalgamation,  chlorination,  or  some  such  process. 
Hence  under  silver  there  are  two  classes  of  mines — lead-silver 
and  high-gi-ade  silver  ores.  Both  have  almost  always  vary- 
ing amounts  of  gold.  The  lead-silver  mines  furnish  also,  as 
noted  above,  by  far  the  greater  portion  of  the  lead  produced  in 
the  United  States.  Ores  adapted  to  lead-silver  metallurgical 
treatment  form,  in  general,  the  oxidized  alteration  products  of 
the  upper  parts  (above  permanent  water  level)  of  deposits  of 
galena  and  pyrites.  They  may  be  well-marked  fissure  veins, 
chimneys,  chambers,  or  contact  deposits.  Ores  which  of  them- 
selves are  adapted  to  other  processes  are  often  worked  in  with 
the  lead  ores,  and  unchanged  sulphides  are  artificially  oxi- 
dized by  roasting  preparatory  to  smelting.  The  localities  are 
taken  up  geographically  from  east  to  west. 

2.08.02.  Lead-Silver  Deposits  in  the  Rocky  Moun- 
tain Region  and  the  Black  Hills.— -The  mines  are  de- 
scribed in  order  from  south  to  north,  beginning  with  New 
Mexico. 

NEW    MEXICO. 

2.08.03.  Example  29.  The  Kelley  Lode.  Oxidized  lead 
ores,  with  some  blende,  calamine,  etc.,  forming  a  contact  de- 
posit betweiin  slates  and  porphyry^  The  ore  body  is  in  the 
Magdalena  Mountains,  thirty  miles  west  of  Socorro,  and  has 
supplied  the  Billings  smelter  at  that  point.  Numerous  other 
ore  bodies  along  the  contact  between  sedimentary  and  eruptive 
rocks  occur  in  the  same  region. 

2.08.04.  Lake  Vallev.     Farther  south  in  Dona  Ana  County 


LEAD  AND  SILVER.  261 

the  mines  of  Lake  Valley  are  and  have  been  worked  upon 
deposits  very  closely  analogous  to  those  of  Leadville,  which 
furnish  the  principal  type.  They  contain  less  lead,  hardly 
enough,  in  fact,  to  he  classed  as  lead -silver  ores,  according  to 
the  recent  valuable  paper  of  Ellis  Clark,  although  earlier 
descriptions  place  greater  emphasis  on  the  presence  of  carbon- 
ates of  this  metal.  According  to  Clark,  the  geological  section 
involved  includes  quartzite  and  limestone,  considered  Silurian, 
600  feet;  Lower  Carboniferous,  black  shale,  100  feet;  green 
shale,  60  feet;  nodular  limestone,  48  feet;  blue  limestone,  24 
feet;  crinoidal  limestone,  125  feet,  and  overlying  limestone,  50 
feet;  about  1,000  feet  in  all.  These  are  penetrated  by  four 
distinct  eruptions  of  igneous  rocks,  hornblende-andesite,  rhyo- 
lite,  obsidian  and  porphyrite.     The  obsidian  is  comparatively 


Fig.  92. — Geological  cross  section  at  Lake  Valley,   JSew  Mexico,  to  show  the 

relations    of  the    ore.     The    black  mass  is  ore;  the    dark  hachures 

in  the  lower  left-hand  corner  are  hlack  shale.     After  Ellis 

Clark,  Trans.  Amer.  Inst.  Min.  Eng.,  XXIV.,  p.  155. 

unimportant,  and  of  the  others  the  porphyrite  is  most  inti- 
mately associated  with  the  ore.  The  ore  bodies  are  always 
connected  with  the  blue  limestone,  and  lie  along  the  contact  of 
this,  either  with  the  porphyrite  or  the  overlying  crinoidal 
limestone.  They  are  in  the  nature  of  large  chutes  or  elongated 
contact  deposits,  very  similar,  as  the  figure  will  indicate,  to 
those  at  Leadville. 

The  ores  are  of  several  varieties  but  the  general  components, 
in  addition  to  the  silver,  are  silica,  oxides  of  iron  and  manga- 
nese, limestone,  some  galena  at  times,  and  some  zinc. 

The  varying  percentages  of  the  silica  and  bases  afford  basic, 
neutral  and  siliceous  ores.  In  the  bonanza  called  the  Bridal 
Chamber,  great    masses    of  horn-silver    were    found.     Many 


262  KEMP'S  ORE  DEPOSITS. 

ores,  and  interesting  metals,  such  as  vanadinite,  descloizite,  etc., 
have  made  the  district  well  known  to  collectors.  Clark  favors 
the  view  that  the  leaching  of  the  porphyrite  (which  is  argentifer- 
ous) during  its  exposure  and  erosion,  by  descending  surface 
waters,  has  been  the  source  of  the  ore.  An  earlier  view  attrib- 
uted it  to  uprising  currents.* 

COLORADO. 

2.08.05.  Example  30.  Leadville.  Bodies  of  oxidized  lead- 
silver  ores,  passing  in  depth  into  sulphides,  deposited  in  much 
faulted  Carboniferous  limestone,  in  connection  with  dikes  and 
sheets  of  porphyry.  Leadville  is  situated  in  a  valley  which  is 
formed  by  the  head  waters  of  the  Arkansas  River.  The  valley 
runs  north  and  south,  being  confined  below  by  the  closing  in 
of  the  hills  at  the  town  of  Granite.  It  is  about  twenty  miles  long 
and  sixteen  broad,  and  even  to  superficial  observation  is  seen  to 
be  the  dried  bottom  of  a  former  lake.  The  mountains  on  the  east 
form  the  Mosquito  range,  a  part  of  the  great  Park  range,  while 
those  on  the  west  are  the  Sa watch,  and  constitute  the  Continen- 
tal Divide  at  this  point.  Leadville  itself  is  on  the  easterly 
side,  upon  some  foothills  of  the  Mosquito  range.  The  eastern 
slope  of  the  Mosquito  range  rises  quite  gradually  from  the 
South  Park  to  a  general  height  of  13,000  feet.  The  range  then 
forms  a  very  abrupt  crest,  with  steep  slopes  looking  westward, 
which  are  due  to  a  series  of  north  and  south  faults  whose  east- 
erly sides  have  been  heaved  upward  as  much  as  7,500  feet.  The 
faults  pass  into  anticlines  along  their  strike.  The  Mosquito 
range  consists  of  crystalline  Archean  rocks,  foliated  granites, 
gneisses,  and  amphibolites,  and  of  over  5,000  feet  of  Paleozoic 
sediments  and  igneous  rocks.  The  former  include  Cambrian 
quartzite,  150  to  200  feet;  Silurian  white  limestone,  160  feet, 
and  quartzite,  40  feet;  Carboniferous  blue  limestone,  200  feet 
(the  chief  ore-bearing  stratum) ;  Weber  shales  and  sandstones, 
2,000  feet;  and  Upper  Carboniferous  limestones,  1,000  to  1,500 
feet.  The  igneous  rocks  are  generally  porphyries.  The  sedi- 
mentary rocks  were  laid  down  in  Paleozoic  time  on  the  shores 

^  E.  Clark,  "The  Silver  Mines  of  Lake  Valley,  N.  M,,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XXIV.,  138,  1894.  Rep.  of  Directo?^  of  the  Mint,  1882,  Lake 
Valley,  p.  341:  Kelley  Lode,  p.  376.  B.  Silliman,  "Mineral  Regions  of 
New  Mexico,"  Trans.  Amer.  Inst.  Min.  Eng.,  X.,  234. 


LEAD  AND  SILVER.  263 

of  the  Archean  Sawatch  Island,  and  were  penetrated  by  the 
igneous  rocks,  probably  at  the  close  of  the  Cretaceous.  They 
Avere  all  upheaved,  folded,  and  faulted  in  the  general  elevation 
of  the  Rocky  Mountains,  about  the  beginning  of  the  Tertiary 
period.  The  intrusion  of  the  igneous  rocks  was  the  prime 
mover  in  starting  ore  deposition,  and  the  solutions  favored  the 
under  sides  of  the  sheets,  along  their  contacts  with  the  blue 
Carboniferous  limestone. 

2.08.06.  The  early  history  of  Leadville  will  be  subsequently 
referred  to  in  speaking  of  auriferous  gravels.  The  lead-silver 
ores  first  became  prominent  in  1877,  although  discovered  in 
1874,  and  by  1880  the  development  was  enormous.  The  region 
grew  at  once  to  be  the  largest  single  producer  of  these  ores,  and 
has  remained  such  ever  since.  The  mines  are  situated  east  of 
the  city  on  the  three  low  hills,  Fryer,  Carbonate  and  Iron,  but 
recently  a  deep  shaft  in  the  city  itself  has  found  the  extension 
of  the  ore  chutes  and  opened  up  great  future  supplies.  The 
ores  have  chiefly  come  in  the  past  from  the  upper  oxidized  por- 
tions of  the  deposits.  Of  late  years,  however,  the  older  and 
deeper  workings  have  been  showing  the  unchanged  sulphurets. 
The  ores  are  chiefly  earthy  carbonate  of  lead,  with  chloride  of 
silver,  in  a  clayey  or  siliceous  mass  of  hydrated  oxides  of  iron 
and  manganese.  In  the  Robert  E.  Lee  mine  silver  chloride 
occurred  without  lead.  Some  zinc  is  also  found,  and  a  long 
list  of  rare  minerals.  Where  the  ore  is  in  a  hard,  siliceous, 
limonite  gangue  it  is  called  hard  carbonate,  but  where  it  is 
sandy  and  incoherent  it  forms  a  soft  carbonate,  or  sand  carbon- 
ate. All  the  older  mines  produce  small  amounts  of  gold,  but 
in  some  newer  developments  the  gold  is  of  more  importance 
than  the  silver.  A  few  ore  bodies  are  found  at  other  horizons 
than  the  Carboniferous.  They  also  run  in  instances  as  much 
as  100  feet  from  the  contact,  and  may  likewise  be  found  in  the 
porphyry,  doubtless  replacing  included  limestone.  They  were 
all  deposited  as  sulphides,  and,  according  to  Emmons,  when 
the  rocks  were  at  least  10,000  feet  below  the  surface. 

In  1891  and  1892  great  interest  centered  in  the  discovery  and 
■development  of  ore  bodies,  whose  values  in  gold  much  ex- 
<3eeded  those  in  silver,  and  which  were  situated  further  east 
from  the  city  of  Leadville  than  the  older  silver  mines.  The 
gold  output  has  now  proved  very  considerable,  although   lim- 


LEAD  AND  SILVER.  2G5 

ited  to  but  few  mines.  The  geological  associations  are  much 
the  same  as  in  the  older  workings,  and  indeed  the  gold  ores 
occur  on  the  extended  lines  of  the  older  chutes,  when  projected 
to  the  eastward. 

2.08.07.  In  the  valuable  monograph  on  the  region,  which  is 
now  a  classic  on  the  subject,  and  which  is  cited  below,  Em- 
mons endeavors  to  prove  the  following  points : 

I.  That  the  ores  were  deposited  from  aqueous  solution. 

II.  That  they  were  originally  deposited  mainly  in  the  form 
of  sulphides. 

III.  That  the  process  of  deposition  involved  a  metasomatic 
interchange  with  the  material  of  the  lock  in  which  they  were 
deposited. 

IV.  That  the  mineral  solutions  or  ore  currents  were  concen- 
trated along  natural  water  channels,  and  followed,  by  prefer- 
ence, the  bedding  planes  at  a  certain  geological  horizon,  but  that 
they  also  penetrated  the  adjoining  rocks  through  cross  joints  and 
cleavage  cracks. 

These  additional  points  are  also  advanced : 

I.  That  the  solutions  came  from  above. 

II.  That  they  were  derived  mainly  from  the  neighboring 
eruptive  rocks. 

2.08.08.  The  first  four  points  are  doubtless  correct,  and  No. 
III.  is  an  important  application  of  the  theory  of  replacement, 
frequently  referred  to  in  the  introduction.  The  last  two  propo- 
sitions merit  less  confidence.  Seven  additional  years  of  mining 
have  brought  many  new  facts  to  light,  and  have  led  others 
(A.  A.  Blow  in  particular,  whose  valuable  paper  is  cited 
below)  to  refer  the  ores  to  upward  rising  currents.  Emmons 
foresaw  this  possibility  and  mentioned  it  on  p.  584  of  his  mono- 
graph. The  amount  of  the  adjacent,  igneous  rocks  is  quite 
insufficient  to  afford  the  ore.  In  alteration  the  galena  has 
passed  through  an  intermediate  stage  of  sulphate  before  chang- 
ing to  carbonate.  These  mines  have  been  important  not  alone 
in  their  own  metallic  products,  but  in  furnishing  the  smelters 
with  oxidized  lead  ores,  they  have  supplied  a  means  of  reduc- 
tion for  many  other  more  refractory  ones,  which  could  be  con- 
veniently beneficiated  through  the  medium  of  lead.^  Much 
copper  occurs  with  the  sulphides  now  met  in  depth. 

'  F.  M.  Amelung,  "The  Geology  of  the  Leadville  Ore  District,"  Eng. 


266  KEMP'S  ORE  DEPOSITS. 

2.08.09.  Example  30a.  Ten  Mile,  Summit  County.  Bod- 
ies of  argentiferous  galena,  pyrite,  blende  and  their  oxidized 
products  replacing  ctr  impregnating  beds  of  Upper  Carbonifer- 
ous limestone,  or  filling  fissure  veins.  The  geological  section 
at  Ten  Mile  resembles  that  of  Leadville,  which  lies  15-20  miles 
south,  but  the  productive  strata  are  in  the  Upper  Carbonifer- 
ous or  Maroon  formation,  instead  of  in  the  Lower  Carboniferous 
or  Leadville  limestone.  The  Maroon  formation  is  chiefly 
sandstones.  It  is  estimated  at  1,500  feet  thick,  and  is  separated 
from  the  Leadville  blue  limestone  by  300  feet  of  Weber  grits. 
It  contains  several  thin  beds  of  limestones  in  connection  with 
which  some  of  the  ores  are  found.  The  ore  bodies  present  at 
least  two  types.  The  first  is  illustrated  by  the  Robinson  mine. 
Fig.  94,  in  which  the  ore  lies  along  two  small  faults  and 
replaces  the  limestone  between  and  on  either  side  of  them.  In 
this  as  in  the  other  mines  the  chief  mineral  in  the  unoxidized  por- 
tion is  pyrite,  or  marcasite  or  pyrrhotite.  With  one  or  the  other 
of  these  are  smaller  amounts  of  galena  and  blende.  The  oxi- 
dized portions  proved  the  richest,  the  others  require  concen- 
tration. The  fissure  vein  type  is  illustrated  by  the  Queen  of  the 
West  mine,  whose  ores  were  found  in  several  parallel  fault 

and  Min.  Jour.,  April  16,  1880,  p.  25.  "On  the  Origin  of  the  Ore," Ibid., 
December  20,  1879.  A.  A.  Blow,  "  The  Geology  and  Ore  Deposits  of  Iron 
Hill,  Leadville,  Colo,,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVIII.,  145,  1889. 
Rec.  Ann.  Rep.  Colo.  School  of  Mines,  1887,  p.  62.  "The  LeadviUe 
Gold  Belt,"  Eng.  and  Min.  Jour.,  January  26,  1895.  Eec.  Maps.  S.  F. 
Emmons,  "Geology  and  Mining  Industry  of  Leadville,"  Monographic, 
U.  S.  Geol.  Survey.  Rec.  Second  Ann.  Rep.  Director  of  U.  S.  Geol.  Sur- 
vey. Rec.  Tenth  Census,  Vol.  XIII.,  p.  76.  F.  T.  Freeland,  "The  Sul- 
phide Deposits  of  South  Iron  Hill,  Leadville,"  I'rans.  Amer.  Inst.  Min. 
Eng.,  XIV.,  181.  C.  Henrich,  "The  Character  of  the  Leadville  Ore 
Deposits,"  Eng.  and  Min.  Jour.,  December  27,  1879,  p.  470.  "Origin  of 
the  Leadville  Deposits,"  Eng.  and  Min.  Jour.,  May  12, 1888,  p.  43.  "On  the 
Evening  Star  Mine,"  Ibid.,  May  7,  1881,  p.  361.  "Leadville  Geology,"  Ibid., 
June  3  and  10,  1882;  "Historical,"  May  30,  April  6,  13,  20,  27,  1878;  also 
many  other  allusions,  1879-81.  R.  W.  Raymond,  "Report  on  the  Little 
Pittsburg  Mine,"  Eng.  and  Min.  Jour.,  June  28,  1879.  L.  D.  Ricketts. 
"Tlie  Ores  of  Leadville,"  Princeton,  1883.  C.  M.  Rolker,  "Notes  on 
Leadville  Ore  Deposits,"  Trans.  Amer.  Inst.  Min.  Eng.,  XIV.,  273,  949. 
F.  L.  Vinton,  " Leadville  and  the  Iron  Mine,"  Eng.  and  Min.  Jour.,  Feb- 
ruary 15,  1879,  p.  110;  also  June  28,  p.  45.  A  series  of  short  papers 
on  "The  Gold  Belt"  was  published  in  1894,  by  the  Leadville  Chamber  of 
Commerce. 


LEAD  AND  SILVER. 


267 


fissures,  as  shown  in  Fig.  95.  The  ores  were  rich  in  the  oxi- 
dized zone,  but  grew  lean  in  the  sulphides.  In  the  White 
Quail  type  the  ores  are  somewhat  less  definitely  circumscribed. 
They  still  form  elongated  replacements,  but  contain  consider- 


SSandstone 
(Shale 
Limestone 


Fig.  94. — Section  through  the  No.  2  ore-ehvte  of  the  Robinson  mine.  Ten-mile 

district,  Colo.     After  S.  F.   Emmonx,   Ten -mile  Special  FoliOt 

U.  S.   Oeological  Sm-i-'y. 


No.3,Sh 


AditNo.*.*^ 


Fig.  95. — Cross-section,  Queen  of  the  West  mine,  I'en-mile  district,  Colo.     2 he 

rich  ore  appears  in  the  darker  vertical  hands.     After  S.  F.  Emmons, 

Ten-mile  Special  Folio,   U.  S.  Oeological  Survey. 

able  quartz,  calcite  and  barite.  They  shade  out  laterally  into 
jasperoid  quartz,  which  is  succeeded  by  barren  limestone.  The 
amount  of  sulphides  is  enormous.* 

'  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  73.  Ten  Mile  Special 
Folio,  1899.  Rec.  The  above  description  has  been  chiefly  drawn  from 
this  folio. 


268  KEMP'S  ORE  DEPOSITS. 

2.08.10.  Example  306.  Monarch  district,  Chafifee  County. 
Oxidized  lead-silver  ores  in  limestone.  The  belt  of  limestones 
south  from  Leadville  contains  some  notable  ore  bodies  in  Chaf- 
fee County.  The  Monarch  district  is  the  most  important.  It 
is  situated  at  the  head  waters  of  a  branch  of  the  South  Arkan- 
sas River.  The  ore  lies  in  limestones  whose  age  is  not  yet  accu- 
rately determined.  The  Madonna  mine  is  the  best  known  and 
has  shipped  much  ore  to  Pueblo.^ 

2.08.11.  Example  30c.  Eagle  River,  Eagle  County.  Galena 
and  its  alteration  product,  anglesite,  in  Carboniferous  lime- 
stone, on  the  contact  between  it  and  quartzite  or  porphyry. 
The  mines  lie  in  the  valley  of  Eagle  River,  on  the  western 
slope  of  the  Continental  Divide.  The  galena  has  changed  to 
the  sulphate,  instead  of  carbonate,  probably  having  been  less 
completely  oxidized  than  at  Leadville,  and  marking  the  inter- 
mediate stage  in  the  process.  The  wall  rocks  lie  quite  undis- 
turbed, having  a  low  dip  of  15°  north,  and  not  being  faulted. 
Lying  lower  than  the  lead-silver  deposits,  and  in  Cambrian 
quartzite,  on  the  contact  with  an  overlying  sandstone,  are  found 

chutes  carrying  gold  in  talcose  clay.^ 

2.08.12.  Example  30d.  Aspen,  Pitkin  County.  Bodies  of 
lead-silver  ores,  largely  oxidized,  occurring  with  much  barite, 
chiefly  at  the  intersections  of  a  series  of  vertical  cross-faults, 
with  two  bed  faults  in  Carboniferous  limestone  and  dolomite; 
but  also  in  less  important  amounts,  although  in  similar  rela- 
tions to  faults,  in  strata  both  older  and  later.  Aspen  is  on  the 
western  slope  of  the  Continental  Divide,  in  the  valley  of  the 
Roaring  Pork,  just  at  the  point,  where  it  crosses  the  contact  of 
crystalline  Archean  gneisses  and  Paleozoic  sediments.  The 
stream  cuts  them  at  right  angles  to  the  strike.  Aspen  Moun- 
tain lies  on  the  south   side,  and   Smuggler  Mountain   on  the 


^  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  79.  Rep.  Director  of 
the  Mint,  1884,  p.  181. 

'  S.  F.  Emmons,  "Notes  on  some  Colorado  Ore  Deposits,"  Colo.  Set. 
Soc,  Vol.  II.,  Part  II.,  p.  100.  E.  E.  Olcott,  "Battle  Mountain  Mining^ 
District,  Eagle  County,  Colorado,"  Eng.  and  Min.  Jour.,  June  11,  1887.  pp. 
417,  438;  Ihid.,  May  21,  1893,  p.  545.  G.  C.  Tilden,  "  Mining  Notes  from 
Eagle  County,"  Ann.  Rep.  Colo.  State  School  of  Mines,  188G,  p.  29. 


LEAD  AND  SILVER. 


269 


270 


KEMP'S  OME  DEPOSITS. 


north.     The  limestone  belt  continues  north  and  south,  and  is 
prospected  over  a  stretch  of  nearly  forty  miles. 

2.08.13.  The  geologicsft  section  at  Aspen  embraces  the 
following  strata,  which  have  been  carefully  determined  and 
measured  by  J.  E.  Spurr.  Upon  the  Archean  granite  rests  the 
Sa watch  formation  of  the  Cambrian,  200  to  400  feet  thick. 
Beginning  as  a  thin  conglomerate,  it  passes  into  a  quartzite 
and  then  into  a  sandy  dolomite.  The  Yule  formation  of  the 
Silurian  is  a  dolomite,  250  to  400  feet  in  thickness.    The  Parting 


Fig.  97a. — Cross  section  of  the  Delia  S.  Mine.  Smuggler  Mountain,  Aspen, 

Colo.     After  J.  E.  Spurr,  Monograph  XXXI.    U.  S.   Geological 

Survey,  Plate  XLII.,  b.  Section  through  the  Durant  and 

Aspen  Mines,  by  D.  Rohlfing,  Idem,  Plate  XL. 

The  black  is  ore. 


Quartzite,  Devonian,  60foet  thick,  lies  above.  The  Carbonifer- 
ous has  three  members.  The  lowest  is  the  Leadville  limestone, 
of  which  200  to  250  feet  is  a  brown  dolomite,  and  100  to  150  feet 
a  blue  limestone,  the  two  being  separated  by  the  "Contact"  bed- 
fault.  Above  the  Leadville  limestone  are  the  Weber  shales  and 
carbonaceous  limestone,  1,000  feet  or  more;  and  the  Maroon 
grits,  4,000  feet.  The  Mesozoic  beds  which  rest  on  the  last 
named  are  very  thick,  but  have  no  important  relation  to  the 
ore. 


LEAD  AND  SILVER.  271 

2.08.14.  Aside  from  the  Archean  granite  there  are  two 
eruptive  rocks  in  the  district.  A  diorite- porphyry  forms  a  sheet 
at  and  below  the  Parting  Quartzite,  and  thickest  at  the  south, 
but  thinning  to  the  north.  A  quartz-porphyry,  very  like  the 
"White  Porphyry"  at  Leadville  (compare  Fig.  93),  is  400  feet 
thick  on  Aspen  Mountain,  but  it  thins  out  both  to  the  north 
and  the  south.  It  appears  near  the  base  of  the  Weber  shales. 
The  age  of  both  the  porphyries  is  probably  late  Cretaceous. 

2.08.15.  After  the  deposition  of  the  Laramie  beds,  of  the 
Cretaceous,  a  compressive  force  from  the  west  developed  an 
overturned  anticline,  which  culminated  in  a  great  fault  along 
Castle  Creek,  to  the  west  of  the  mines.  A  syncline  was  pro- 
duced on  the  east  limb  of  the  great  anticline,  and  was  later 
domed  upward  by  an  uplift,  which  gave  the  trough  a  marked 
pitch  to  the  north.  During  the  folding  two  faults  were  produced 
parallel  with  the  bedding  of  the  Leadville  limestone.  One  runs 
along  at  the  contact  of  the  dolomite  and  the  blue  limestone 
(the  ** Contact"  fault);  the  other  follows  the  contact  of  the  blue 
limestone  and  the  Weber  shales  (the  "Silver"  fault).  Many 
cross-faults  were  also  formed  at  about  this  time,  which  inter- 
sected the  bed-faults,  but  along  which  movement  seems  to  be 
still  in  progress.  At  a  certain  stage  ore-bearing  solutions 
appear  to  have  circulated  along  the  bed-faults,  and  are  thought 
by  J.  E.  Spurr,  to  have  been  precipitated  by  other  solutions  in 
the  cross- faults,  so  that  the  shattered  rock  at  the  intersections 
became  replaced  with  ore.^ 

2.08.16.  Example  30e.  Eico,  Dolores  County.  Contact 
deposits  of  lead-silver  ores,  in  Carboniferous  limestones,  along 


»  D.  W.  Brunton,  "Aspen  Mountain :  Its  Ores  and  Mode  of  Occurrence, " 
Eng.  and  Min.  Jour.,  July  14  and  21,  1888,  pp.  22,  42.  S.  F.  Emmons, 
"Preliminary  Notes  on  Aspen,"  Proc.  Colo.  Sci.  Soc,  Vol.  II.,  Part  III., 
p.  251.  Rec.  C.  Henrich,  "Notes  on  the  Geology  and  on  some  of  the 
Mines  of  Aspen  Mountain,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVII.,  156,  A. 
Lakes,  "Geology  of  the  Aspen  Mining  Region,"  Ann  Rep.  Colo.  School  of 
Mines,  1886.  W.  E.  Newberry,  "Notes  on  the  Geology  of  the  Aspen 
Mining  District,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVII.,  273,  1889.  Rec. 
L.  D.  Silver,  "Geology  of  the  Aspen  (Colo.)  Ore  Deposits, "  Eng.  and  Min. 
Jour.,  March  17  and  24,  1888.  J.  E.  Spurr,  "Geology  of  Aspen  Mining 
District,"  U.  S.  Oeol.  Survey,  Monograph  XXXI.,  1899.     Rec. 


272  KEMP'S  ORE  DEPOSITS. 

intrusive  porphyries.  Considerable  base  bullion  has  been 
shipped.  There  are  coals  in  the  vicinity,  but  the  operation  of 
the  smelter  has  been'  somewhat  intermittent.  The  Newman 
Hill  mines  are  mentioned  under  "Silver."  ^ 

Note. — Example  30/  will  be  found  after  Example  31,  which 
has  been  inserted  for  geographical  reasons. 

2.08.17.  Example  31.  Red  Mountain,  Ouray  County. 
Oxidized  lead-silver  ores  passing  in  depth  into  sulphides,  in 
large  and  small  cavities,  in  knobs  of  silicified  andesite.  The 
cavities  have  a  close  resemblance  to  caves,  but  differ  from  ordi- 
nary caves  in  not  being  in  limestone.  They  permeate  the 
mountain  in  an  irregular  way,  and  mark  the  courses  of  old  hot 
spring  conduits.  The  andesite  is  generally  altered  to  a  mass 
of  quartz,  but  the  process  is  thought  by  S.  F.  Emmons  to  have 
taken  place  at  a  considerable  depth,  and  that  the  quartz  is  a 
residual  deposit  left  by  the  removal  of  more  soluble  elements 
of  the  andesite.  T.  B.  Comstock  regards  them  as  hot  spring 
deposits.^ 

SOUTH    DAKOTA. 

2.08.18.  Example  30/.  Galena  (town),  in  the  Black  Hills. 
Deposits  of  galena  in  part  altered  to  carbonate,  in  Cambrian 
(Potsdam)  sandstone,  near  intruded  sheets  of  trachyte.  The 
ore  occurs  in  local  enrichments  distributed  at  irregular  inter- 
vals through  the  sandstone.  It  is  rarel}'  found  in  the  overly- 
ing limestones  of  the  Carboniferous.  The  ore  bodies  are  closely 
akin  to  the  so-called  * 'siliceous,  "or  "Potsdam"  gold  ores,  later 
described.    Galena  and  Carbonate  are  the  best  known  localities.^ 

*  M.  C.  Ihlseng,  "Review  of  the  Mining  Regions  of  the  San  Juan," 
Ann.  Rep.  Colo.  School  of  Mines,"  1885,  p.  43. 

'  T.  B.  Comstock,  "  Hot  Spring  Deposits  in  Red  Mountain,  Colorado," 
Trans.  Artier.  Inst.  Min.  Eng.,  XVIII.,  261.  S.  F.  Emmons,  "Notes  on 
Some  Colorado  Ore  Deposits,'  Proc.  Colo.  Sci.  Sac.,  Vol.  II.,  Part  II.,  p. 
97.  M.  C.  Ihlseng,  "Review  of  the  Mining  Interests  of  the  San  Juan 
Region,"  Ann.  Rep.  Colo.  School  of  Mines,  1885,  p.  46.  T.  E.  Schwartz, 
"  The  Ore  Deposits  of  Red  Mountain,  Colorado,"  Trans.  Amer.  Inst. Min. 
Eng.,  XVIII.,  139,  1889;  Proc.  Colo.  Sci.  Soc.,  Vol.  HI.,  Part  I.,  p.  77. 

'  F.  R.  Carpenter,  "Ore  Deposits  of  the  Black  Hills  of  Dakota,"  Trans. 
Amer.  Inst.  Min.  Eng.,  1889,  Vol.  XVII.,  p.  570.  See  also  report  by  Dr. 
Carpenter  on  the  geology,  etc. ,  of  the  Black  Hills,  to  the  trustees  of  the 
Dakota  School  of  Mines,  1888,  p.  124.  S.  F.  Emmons,  Tenth  Census,  Vol. 
XIII.,  p.  91. 


LEAD  AND  SILVER.  273 

MONTANA — IDAHO. 

2.08.19.  Example  32.  Glendale,  Beaver  Head  County. 
Ore  bodies  of  argentiferous  galena,  zincblende,  copper  and  iron 
pyrites,  and  their,  oxidation  products,  occurring  parallel  with 
the  stratification  planes  of  a  blue-gray  limestone,  of  age  not  yet 
determined.  These  deposits  constitute  the  Hecla  mines,  and 
are  in  the  southwestern  part  of  the  State.  They  offer  some 
parallel  features  with  those  of  southeastern  Missouri.  (Exam- 
ple 23.)  They  differ  from  Example  30  in  not  being  associated, 
so  far  as  known,  with  igneous  rocks.  ^ 

2.08.20.  Example  32a.  Wood  River,  Idaho.  Bodies  of 
argentiferous  galena  and  alteration  products,  irregularly  dis- 
tributed in  limestone,  of  age  as  yet  undetermined.  Southwest- 
ern Idaho  is  largely  formed  of  granite,  southeastern  is  cov- 
ered by  the  immense  fissure  outpourings  of  basalt  along  the 
Snake  River.  North  of  these,  and  on  the  flanks  of  the  gran- 
ite, are  slates  and  limestones,  especiallj^  on  the  Wood  River.  The 
latter  contain  the  lead-silver  ores.  They  are  not  in  immediate 
association  with  igneous  rocks,  and  from  published  descriptions 
appear  to  be  somewhat  irregularly  distributed,  although  possi- 
bly connected  with  fissures.  The  stuctural  relations  with  Ex- 
ample 23  may  again  be  referred  to.  The  neighboring  slates 
and  granite  contain  gold  and  silver  veins,  which  are  taken  up 
later  on.  Several  small  smelters  have  been  erected  in  the 
region,  and  have  been  intermittently  operated.  The  country 
is  really  in  the  northern  end  of  the  Great  Basin. ^ 

2.08.21.  Example  33.  Wickes,  Jefferson  County,  Mont. 
Fissure  veins  near  the  contact  of  granite  and  liparite,  but  cut- 
ting both  rocks  and  carrying  in  a  gangue  of  quartz  the  ores, 
galena,  zincblende,  copper  and  iron  pyrites,  and  mispickel. 
The  liparite  is  said  by  Lindgren  to  be  Cretaceous  or  Tertiary. 
Wickes  is  just  south  of  Helena,  and  was  one  of  the  first  places 
in  the  West  to  establish  successful  concentration.  There  are 
two  companies,  the  Helena  and  the  Gregory,  both  large  pro- 
ducers. 

'  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII. ,  p.  97. 

^  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  55.  Eng.  and  Min.  Jour., 
July  2, 1887,  p.  3.  Rep.  Director  of  the  Mint,  1882,  p.  198.  G.  H.  Eldredge, 
XVI. ;  Ann.  Rep.  Dir.  U.  S.  Oeol.  Survey,  II.,  264.  Rec.  J.  B.  Hastings, 
Eng.  and  Min.  Jour.,  March  25,  1895.  268. 


274  KEMP'S  ORE  DEPOSITS. 

2.08.22.  Example  34.  Coeur  d'Alene,  Idaho.  GaleDa  and 
very  subordinate  alteration  products,  in  a  mineralized  zone 
having  a  well-marked  footwall  and  an  impregnated,  brecciated 
hanging  of  the  same  rock.  The  ore  is  in  large  chutes,  which 
fill  innumerable  small  fractures  in  the  rock.  The  mines  are  in 
Wardner  Canon,  in  the  Bitter  Root  Mounfciins,  northern 
Idaho.  The  rocks  are  quartzite,  and  thin  beds  of  schists,  much 
folded  along  east  and  west  axes.  In  this  way  they  became 
faulted  and  shattered,  and  in  the  principal  mineral  belt  afforded 
an  opportunity  for  the  ore  to  deposit.  The  gangue  is  siderite. 
The  mines  are  extremely  productive  and  are  the  chief  sources 
of  ore  supply  for  lead  smelters  in  Montana  and  on  the  Pacific 
coast. ^     Detailed  descriptions  are  much  needed. 

UTAH. 

2.08.23.  Example  35.  Bingham  and  Big  and  Little  Cot- 
tonwood Canons,  Utah.  Bed  veins,  often  of  great  size,  contain- 
ing oxidized  lead-silver  ores  above  and  galena  and  pyrite  below 
the  water  level,  in  Carboniferous  limestones,  or  underlying 
quartzite,  or  on  the  contact  between  the  two.  The  mines  are 
situated  in  the  Oquirrh  and  Wasatch  Mountains,  southwest  and 
southeast  of  Salt  Lake  City,  in  canons  well  up  toward  the 
summits.  The  region  is  much  disturbed,  and  there  are  great 
faults  and  porphyry  dikes  and  knobs  of  granite  associated  with 
the  sedimentary  rocks.  The  ores  occur  in  belts,  extending  con- 
siderable distances,  and  these  in  places  have  the  rich  chutes  or 
chimneys  of  oxidized  products.  In  Bingham  Canon  an  im- 
mense bed  of  auriferous  quartz  is  found,  overlying  the  lead 
zone  and  next  the  hanging.  Some  peculiarity  about  the  gold 
prevents  its  easy  treatment,  but  much  of  the  rock  is  very  low 
grade.  Recently  very  extensive  deposits  of  copper  ore  have 
been  found  in  the  Highland  Boy.  Other  fissure  veins  in  the 
massive  rock  of  the  region  are  known,  but  are  of  less  import- 
ance. The  general  geological  relations  suggest  the  deposits 
mentioned  under  Example  30  and  subtypes.  The  mines  were 
the  occasion  of  the  first  development  of  the  lead-silver  smelters 
in  the  West,  and  have  made  Salt  Lake  City  an  important  cen- 

*  J.  E.  Clayton,  "The  Coeur  d'Alene  Silver-lead  Mines,"  Eng.  and  Min. 
Jour.,  February  11,  1888,  p.  108. 


si   ^ 


Fig.  99. — View  of  thet(ncn  of  Mammoth,  Tintic  district,  Utah.    From 
a  photograph  by  L.  E.  Riter,  Jr. ,  1898. 


Fig.  \00.— Bullion  and  Beck  Mine  and  Mill  Eureka,  Tintic  district,  Utah. 
From  a  photograph  by  L.  E.  Riler,  Jr.,  1898. 


LEAD  AND  SILVER.  275 

ter  of  the  industry.  The  Telegraph  group,  the  Emma,  Flag- 
staff, and  others  were  famous  mines  in  their  day.  As  will 
appear,  nearly  all  the  Utah  mines  are  productive  of  lead-silver 
ores. 

2.08.24.  Example  35a.  Tooele  County.  Bed  veins  in 
limestone,  or  between  it  and  quartzite,  and  containing  lead- 
silver  ores  with  others,  in  rich  chutes.  The  deposits  occur  in 
the  west  side  of  the  Oquirrh  range,  in  Ophir  and  Dry  canons, 
over  the  divide  from  Bingham.  The  principal  mine  is  the 
Honorine.  Fissure  veins  also  occur  in  the  region,  but  are  of 
less  importance.  The  Deep  Creek  district,  near  the  Nevada 
line,  is  mentioned  under  2.11.04.^ 

2.08.25.  Example  3o6.  Tintic  District.  Ore  beds  or  belts, 
three  in  number,  and  one  to  three  miles  long,  generally  paral- 
lel with  the  stratification  of  vertical  blue  limestones,  but  some- 
times running  across  them.  The  ore-bearing  zone  is  from  300  to 
600  feet  wide  in  at  least  one  belt,  and  bears  in  places  rich  chutes 
of  cai  bonate  ore.  The  Crismon-Mammoth  has  been  referred  to 
under  "Copper'*  (Example  20g),  as  it  contains  much  copper. 
The  ore  is  thought  by  Hollister  to  have  replaced  the  limestone.^ 

Passing  mention  should  also  be  made  that  lead-silver  ores 
occur  in  Summit  County,  at  the  Crescent  and  other  mines. 

2.08.26.  Example  30^.  Horn  Silver  Mine,  Beaver  County. 
A  great  contact  fissure  between  a  rhyolite  hanging  wall  and  a 
limestone  foot  wall,  and  carrying,  at  the   Horn   Silver  mine, 

oxidized  lead-silver  ores,  chiefly  anglesite,  with  considerable 

• 

*  W.  p.  Blake,  "Brief  Description  of  the  Emma  Mine,"  Amer.  Jour. 
Sei.,  ii,  n.,  216.  C.  E.  Fenner.  "The  Telegraph  Mine,"  School  of  Mine» 
Quarterly,  July,  1893.  O.  J.  Hollister,  "  Gold  and  Silver  Mining  in  Utah," 
Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  3.  Rec.  D.  B.  Huntley,  Tenth 
Census,  Vol.  XHI,  p.  407.  G.  Lavagnino,  "  The  Old  Telegraph  Mine,** 
Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  '2h.  "  Little  Cottonwood  and  Bing- 
ham, Utah,"  Eng.  and  Min.  Jour..  August  14,  1880,  p.  106;  also  July  19, 
1889.  J.  S.  Newberry,  School  of  Mines  Qyjuirterbj,  1884,  p.  329.  R.  W. 
Raymond,  Mineral  Resources  West  of  the  Rocky  Mountains,  1868-76,  and 
J.  R.  Brown,  llrid.,  1867-68.  Ann.  Reps,  of  Director  of  the  Mint.  B.  Sfl- 
liman,  'Geological  and  3Iineralogical  Notes  on  Sc«ne  Mining  Di«(tricts  of 
Utah,"  Amer.  Jour.  Sci.,  iii.,  HI .  195. 

*  D.  B.  Huntley  and  O.  J.  HoUister.  as  above,  under  last  focAnote.  J. 
S.  Newberry,  Eng.  and  Min.  Jour.,  September  13  and  20,  1879.  A  report 
on  the  district  is  in  press  with  the  U.  S.  Geological  Survey. 


276  KEMP'S  ORE  DEPOSITS. 

barite,  and  with  many  other  rarer  minerals.  The  town  of 
Frisco,  containing  the  mine,  is  at  the  southern  end  of  the 
Grampian  Mountains.  The  great  fissure  is  known  for  two  miles, 
but  is  proved  valuable  only  between  the  lines  of  the  Horn  Sil- 
ver mine.  It  strikes  north  and  south  and  dips  70°  east.  In 
the  neighborhood  of  the  vein  the  rhyolite  is  largely  altered  to 
residual  clay.  The  mine  is  very  dry,  and  the  entire  region 
lacks  good  water.  The  vein  in  general  varies  from  20  to  60 
feet,  but  has  pinched  twice  in  going  down,  and  of  late  years 
has  largely  ceased  producing,  although  there  may  yet  be  much 
ore  below.  The  ores  are  smelted  near  Salt  Lake,  and  the  base 
bullion  is  refined  at  Chicago.  Some  free  milling  ore  has  been 
afforded.^ 

2.08.27.  Example  33a.  Carbonate  Mine,  Beaver  County. 
A  fissure  vein  in  hornblende  andesite,  filled  with  rounded  frag- 
ments of  wallrock,  which  are  cemented  by  residual  clay  and 
galena.  Some  oxidized  products  occur  near  the  surface.  The 
mines  are  two  and  a  half  miles  northeast  of  Frisco,  but  are  in 
a  different  eruptive  rock  from  that  forming  the  walls  of  the 
Horn  Silver.  The  literature  is  the  same  as  for  Example  30g, 
especially  Hooker,  1.  c.  p.  470. 

2.08.28.  Example  326.  Cave  Mine,  Beaver  County.  Cham- 
bers irregularly  distributed  in  the  limestone,  and  more  or  less 
filled  with  limonite  and  oxidized  lead-silver  ores.  Small  lead- 
ers of  ores,  which  mark  old  conduits,  connect  the  chambers. 
Up  to  1880  five  large  and  fifteen  small  chambers  had  been 
found.  They  are  of  very  irregular  shape,  and  have  a  vacant 
space  of  from  one  to  ten  feet  between  the  ore  and  the  roof. 
This  deposit  was  the  typical  one  cited  by  Newberry  as  illustrat- 
ing the  chamber  or  cave  form  of  deposit.  According  to  this 
view,  the  chambers  were  formed  before  the  ore  was  brought  in. 

It  is  also  possible  that  the  ore  bodies  have  been  deposited  by 
replacement  of  the  limestone  with  sulphides,  as  is  known  abun- 
dantly elsewhere,  and  that  the  alteration  of  these  to  oxides  has 
occasioned  the  apparent  caves.  The  products  of  the  mine 
afford  but  5  to  7%  lead,  but  are  valuable  as  an  iron  flux  to  the 

*  O.  J.  Hollister,  "  Gold  and  Silver  Mining  in  Utah,"  Trans.  Amer.  Inst. 
Min.Eng.,  XVI.,  3.  Rec.  W.  A  Hooker,  Report  quoted  in  the  Tenth 
Census,  Vol.  XIII.,  p.  464. 


LEAD  AND  SILVER.  277 

neighboring  smelters.     The  mines  are  in   the  Granite  range, 
seven  miles  southeast  of  Milford.* 

Note. — Although  the  larger  part  of  the  Utah  mines  are  for 
lead  and  silver,  several  others  of  great  importance  will  be  taken 
up  under  "Silver"  itself. 

NEVADA. 

2.08.29.  Example  36.  Eureka.  Bodies  of  oxidized  lead- 
silver  ores  in  much  faulted  and  fractured  Cambrian  limestone, 
with  great  outbreaks  of  eruptive  rocks  near.  The  Eureka  geo- 
logical section  is  one  of  the  most  interesting  in  the  entire  coun- 
try, and  involves  some  30,000  feet  of  Paleozoic  strata,  divided 
as  follows;  Cambrian  quartzite,  limestone,  and  shale,  7,700 
feet;  Silurian  limestone  and  quarztite,  5,000  feet;  Devonian 
limestone  and  shale,  8,000  feet;  Carboniferous  quartzite,  lime- 
stone, and  conglomerate,  9,300  feet.  These  have  afforded  some 
extremely  valuable  materials  for  comparative  studies  with 
homotaxiai  strata  in  the  East.  The  ore  occurs  especially  in 
what  is  called  the  Prospect  Mountain  limestone  of  the  Cam- 
brian, one  smaller  deposit  being  also  known  in  Silurian  quartz- 
ite. The  limestone  has  been  crushed  and  shattered  along  a 
great  fault,  and  through  its  substance  ore  solutions  have  circu- 
lated, replacing  it  in  part  with  large  bodies  of  sulphides  which 
have  afterward  become  oxidized  to  a  depth  of  1,000  feet.  The 
ore  bodies  were  puzzling  as  regards  their  classification,  and  a 
famous  mining  suit,  with  many  interpretations  from  various 
experts,  resulted.  The  alteration  of  the  ore  has  caused  shrink- 
age, and  the  formation  of  apparent  caves  over  it.  But  there 
are  many  empty  caves,  formed  by  surface  waters  long  after  the 
ore  was  deposited,  and  J.  S.  Curtis  very  clearly  shows  that  the 
ore  bodies  originated  by  replacement.  All  are  connected  with 
more  or  less  strongly  marked  fissures  which  formed  the  con- 
duits. Mr.  Curtis  made  a  careful  series  of  assays  of  the  neigh- 
boring igneous  rocks  to  find  some  indication  of  the  source  of 
the  ore.  A  quartz  porphyry  gave  significant  results,  and  to 
this  the  metals  are  referred,  the  portions  of  the  mass  at  a  great 

*  O.  J.  Hollister,  "Gold  and  Silver  Mining  in  Utah,"  Trans.  Amer.  Inst. 
Min  Eng.,  XVI.,  3.  D.  B.  Huntley,  Tenth  Census,  Vol.  XIII  ,  p.  474.  J. 
S  Newberry,  School  of  Mines  Quarterly,  March.  1880.  Reprint,  p.  9.  Cf. 
also  J.  B  Kimball.  "The  Silver  Mines  of  Eulalia,  Chihuahua,"  Amer. 
Jour.  Sci  ,  ii..  XLIX  ,  161. 


278 


KEMP'S  ORE  DEPOSITS. 


depth  are  considered  to  have  furnished  them.  Eureka  was 
one  of  the  first  places  in  this  country  where  the  hypothesis  of 
replacement  was  applied  to  ores  in  limestone.  The  district  is 
now  far  less  productive  than  it  was  fifteen  or  twenty  years  ago. ^ 


-^"^Y^^Vf^^^^^ 

-S 

^^^^V^ 

^"^^l      ^^^  /v^  1  /     /\     y*"^          i\      f — ^ 

;j_^ 

\      A     L^^      Y\Crushed/\- 

nestoae^ 

^^^Jfl^^Wfgii^w^S 

^PFOspec1:r^.Mtn 

Quartzite 

3 

/  \  1 1           .^^htM  mestone^ 

Fig.  \Q\.— Section  at  Eureka,  Nev.     Reproduced 
plate  by  J.  S.  Curtis,  Monograph  VI.,  U. 

in 
S. 

li? 
0 

__-:rj_-:'^- 
— -n— -X^ 

le  work  afi 
eol.  Survey 

er  colored 

»  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  32.  Rec.  W.  P.  Blake, 
" The  Ore  Deposits  of  the  Eureka  District,  Nevada."  Trans.  Amer.  Inst. 
Min.  Eng.,  VI.,  554.  J.  S.  Curtis,  "Silver-lead  Ore  Deposits  of  Eureka. 
Nev.."  Monograph  VII.,  U.  S.  Geol.  Survey.  A.  Hague.  "Geology  of  the 
Eureka  District,"  Monograph  XX.,  U.  S.  Geol.  Survey.  Abstract  in  Third 
Ann.  Rep.  Director  U.  S.  Geol.  Surveg.  W.  S.  Keyes,  "Eureka  Lode  of 
Eureka,  Nev.,"  Trans.  Amer.  Inst.  Min.  Eng.,  VI.,  344.  J.  S.  Newberry, 
School  of  Mines  Quarterly,  March,  1880.  R.  W.  Raymond,  "The  Eureka- 
Richmond  Case,"  Trans.  Amer.  Inst.  Min.  Eng.,  VI.,  371.  C.  D.  Walcott, 
"Paleontology  of  the  Eureka  District,"  Monograph  VIII ,  U.  S.  Geol. 
Survey. 


LEAD  AND  8ILVER.  279 

ARIZONA— CALIFORNIA. 

2.08.30.  Comparatively  small  amounts  of  lead  ores  are  ship- 
ped from  Arizona  from  time  to  time,  chiefly  from  Cochise 
County  (Tombstone  region)  and  Pima  Count}'  (Tucson  region). 
They  will  be  mentioned  under  *' Silver."  Insignificant  amounts 
are  also  afforded  by  California  (about  $2,000  in  1889),  mostly 
from  Inyo  County.  (See  Eleventh  Census^  Bull,  No,  80,  June 
18,  1891.) 


CHAPTER  IX. 

SILVER  AND   GOLD.— INTRODUCTORY  :   EASTERN  SILVER  MINES 

AND     THE     ROCKY     MOUNTAIN    REGION    OF    NEW 

MEXICO   AND   COLORADO. 

2.09.01.  The  two  ''precious"  metals  are  so  generally  asso- 
ciated that  they  cannot  be  separately  treated.  While  endeav- 
oring to  preserve  the  distinctive  impression  given  by  examples, 
i\  is  practically  impossible  to  set  forth  all  the  widely  varying^ 
phenomena  of  the  silver-gold  veins  of  the  West  in  any  other 
than  an  approximate  way.  Hence  geographical  considerations 
are  placed  first  and  where  markedly  similar  ore  bodies  in  dif- 
ferent States  are  to  be  grouped  together  cross  references  are 
given.  The  following  general  examples  have  been  made  be- 
cause their  individual  features  are  based  on  those  geological 
relations  which  are  most  vitally  concerned  with  questions  of 
origin. 

2.09.02.  Example  37.  Veins  containing  the  precious  met- 
als usually  with  pyrite,  galena,  chalcopyrite,  and  less  common 
sulphides,  sulpharsenides,  sulphantimonides,  etc.,  in  igneous 
rocks.  No  special  subdivision  is  made  on  the  character  of  the 
gangue,  which  may  be  quartz,  calcite,  barite,  fluorite,  etc.,  one 
or  all.  The  first  named  is  commonest.  A  great  and  well- 
defined  original  fissure  is  not  necessarily  assumed,  but  some 
crack,  or  joint  or  crushed  strip  must  have  directed  the  ore- 
bearing  solutions,  which  may  have  then  replaced  the  walls  in 
large  measure.  For  other  structural  features  see  the  discussion 
of  veins  (J. 05. 01);  compare  also  Example  17,  Butte,  Mont. 

Example  37a.  Replacements  more  or  less  complete  of 
igneous  dikes,  which  have  usually  been  described  as  porphyry. 
Compare  Example  17a  under  "Copper"  (Gilpin  County,  Colo- 
rado), and  Example  20(i  (Santa  Rita,  N.  M.).  Ore  and  gangue. 
where  the  matrix  is  not  the  dike  rock,  as  in  Example  37. 


SILVER  AND  GOLD.  281 

Example  38.  Contact  deposits  between  two  kinds  of  igneous 
rock  or  between  two  different  flows.  Ore  and  gangue  as  in 
Example  37. 

Example  39.  Agglomerates  of  rounded,  eruptive  boulders, 
bombs,  etc.,  in  abandoned  volcanic  necks  or  conduits,  and 
coated  with  ores.  The  Bassick  mine  of  Custer  County,  Colo- 
rado, is  the  only  example  of  an  ore  deposit  of  this  kind  yet 
identified. 

Example  40.  Contact  deposits  between  igneous  and  sedi- 
mentary rocks.  No  subdivisions  are  made  on  the  kind  of  rocks. 
Ore  and  gangue  as  in  Example  37.  The  ore  body  may  replace  a 
calcareous  rock  along  the  under  side  of  an  intruded  sheet.  Com- 
pare also  Example  20,  '* Arizona  Copper";  Example  21a, 
'*Triassic  Copper";  Example  30,  *'Leadville" ;  and  Example 
30gr,  "Horn  Silver  Mine." 

Example  41.  Veins  in  sedimentary  rocks,  generally  cutting 
the  bedding,  but  at  times  parallel  with  it.  Lateral  enlarge- 
ments are  frequent.  The  ore  body  may  be  largely  due  to  the 
replacement  of  some  calcareous  rock,  such  as  limestone  or  lime- 
shales,  beneath  some  relatively  impervious  bed.  Ore  and  gan- 
gue as  in  Example  37. 

Example  42.  Veins  cutting  both  sedimentary  and  igneous 
rocks,  and  therefore  due  to  disturbances  after  the  intrusion  of 
the  latter.     Ore  and  gangue  as  in  Example  37. 

No  special  examples  are  made  for  metamoiphic  rocks. 

2.09.03.  Minerals  containing  silver  or  gold. 

Ag.  S.         As.       Sh.         CI. 

Native  silver 100 

Argenite  (silver  glance),  AggS 87.1     13.9     

Proulite  (light  ruby  silver) ,  SAg^S.  As^Sg . .  65 . 5    19.4    15.1     

Pyrargerite  (dark  ruby  silver) ,  SAg^S. SbaSg  60 .  17.8     ....     22 . 2     .... 

Stephanite  (brittle  silver) ,  SAg^S. SbgSg ....  68 . 5  16.2     ....     15.3     .... 

Cerargerite  (horn  silver) ,  AgCl 75 . 3     24 . 7 

Silver  also  occurs  with  galena  (Cf.*'Lead")  and  with  tetra- 
hedrite  (Cf.  ** Copper").  Gold  occurs  combined  with  tellu- 
rium in  tellurides;  mechanically  mingled  with  pyrites;  and  as 
the  uncombined  native  metal.  From  a  metallurgical  point  of 
view  the  ores  of  the  precious  metals  are  divided  into  two 
classes.  1.  Those  whose  amount  of  precious  metal  amalga- 
mates readil.y  with  quicksilver,  and  is  thus  obtained  with  com- 


382  KEMP'S  ORE  DEPOSITS. 

parative  ease — the  free  milling  ores.  2.  Those  which  require 
roasting  or  some  previous  treatment  before  amalgamation, 
chlorination,  or  similar  process,  or  which  must  be  smelted  pri- 
marily for  lead  or  copper,  from  which  the  precious  metals  are 
afterward  extracted — the  rebellious  ores.  In  the  subsequent 
description  the  endeavor  has  been  made  to  work  from  the  dis- 
tinctively silver  mines  to  those  of  gold,  where  geographical^ 
possible.^ 

The  precious  metals  seem  to  have  been  derived  in  almost  all 
cases  from  deep-seated  sources,  and  presumably  from  igneous 
rocks,  even  though  they  may  now  be  found  in  sediments  or 
metamorphic  rocks.  The  valuable  and  thorough  researches  of 
J.  R.  Don  upon  the  Australian  gold-bearing  reefs,  the  neigh  bor- 
ing wall  rocks,  and  the  sea  water  as  a  possible  source  of  the 
precious  metal  have  led  to  increased  faith  in  its  derivation  by 
uprising  solutions.     Both  Blake  and  Merrill  have  discovered 

^  Ann.  Reps.  Directors  of  the  Mint.  Rec.  W.  P.  Blake,  "The  Various 
Forms  in  which  Gold  Occurs  in  Nature, "  Rep.  Director  of  the  Mint,  1884, 
p.  573.  Rec.  "Gold  in  Granite  and  Plutonic  Rocks,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XXVI.,  290,  1896.  Brown,  Raymond,  and  others,  1868  to  1876, 
"Mineral  Resources  West  of  the  Rocky  Mountains.'  Annual.  T.  C. 
Chamberlin,  "On  the  Geological  Distribution  of  Argentiferous  Galena," 
Geol  of  Wis.,  Vol.  IV.  Cumenge  and  Robellaz,  "L'Or  dans  la  Nature," 
Paris,  1879.  L.  De  Launay,  "Contribution  a  letude  des  Gites  Metal- 
liferes,  Annates  des  Mines,  August,  1897,  108.  J.  R.  Don,  "The  Genesis 
of  Certain  Auriferous  Lodes,"  Trans.  Amer.  List.  Min.  Eng.,  XXVII.,  564, 
1897.  Rec.  J.  F.  Kemp,  "Geological  Occurrence  and  Associates  of  the 
Telluride  Gold  Ores,"  The  Mineral  Industry,  VI.,  295-320,  1898.  Clarence 
King,  "  Production  of  the  Precious  Metals  in  the  United  States,"  fi^ecoJid 
Ann.  Rep.  Director  U.  S.  Geol.  Survey,  p.  333.  A.  G.  Lock,  Gold,  1882.  G. 
P.  Merrill,  "Gold  in  Granite,"  Amer.  Jour,  of  Sci.,  April,  1896,  309.  Mineral 
Resources  of  the  U.  S. ;  annual  publication  of  the  Geological  Survey.  R. 
I.  Murchison,  "General  View  of  the  Conditions  under  which  Gold  is  Dis- 
tributed," Quar.  Jour.  Geol.  Soc,  VII.,  134.  Also  in  Siluria  and  Amer. 
Jour.  Sci.,  ii.,  XVIII.,  301.  J.  S.  Newberrj^  "On  the  Genesis  and  Distri- 
bution of  Gold,"  School  of  Mines  Quarterly,  III.,  No.  1,  and  Eng.  and  Min. 
Jour.,  December  24  and  31,  1881,  pp.  416,  437.  R.  Pearce,  "On  the  Ores 
of  Gold,"  etc.,  Colo.  Sci.  Soc,  III.,  p.  237.  J.  A.  Phillips,  Ore  Deposits, 
1884.  The  Mining  and  Metallurgy  of  Gold  and  Silver,  1867.  Tenth  Cen- 
sus Report  on  the  Precious  Metals.  Albert  Williams,  ' '  Popular  Fallacies 
Regarding  Precious  Metal  Ore  Deposits,"  Fourth  Ann.  Rep.  Dir.  U.  S. 
Geol.  Survey,  1884.  J.  H.  L.  Vogt,  Zeitschrift  fur  prakt.  Geologic,  Sep 
tember,  1898,  321.  "Ueber  die  Bildung  des  Gediegen  Silbers,"  etc.,  Idem, 
April,  1899,  113. 


SILVER  AND  GuLD.  283 

gold  in  granite,  and  Moricke,  as  earlier  cited,  1.03.06,  observed  it 
in  obsidian. 

2.09.04.  Example  22a.  Atlantic  Border.  Already  men- 
tioned (2.05.02),  the  region  is  onl}-  of  historical  interest  as  af- 
fording silver,  although  lately  some  attention  has  been  directed 
to  Sullivan,  Me.,  where  the  veins  have  pyrite  and  probably 
stephanite,  in  a  quartz  gangue,  in  slates,  associated  with  gran- 
ite knobs  and  trap  dikes,  which  are  of  later  age  than  the  veins. 
Some  silver  is  generally  found  in  the  galena  of  the  Eastern 
States,  but  the  ores  have  never  yet  proved  abundant  enough  to 
T)e  important.^ 

Mention  may  also  be  made  at  this  point  of  the  argentiferous 
galena  veins  along  the  Ouachita  uplift  of  Arkansas.  A  few 
are  known,  usually  with  Trenton  shales  or  slates  for  walls. 
They  are  low  grade,  and  though  once  the  basis  of  a  small  ex- 
citement, their  production  has  never  been  serious.  Additional 
reference  to  the  region  will  be  found  under  "Antimony." 
Some  mines  of  the  latter  metal  are  stated  by  W.  P.  Jenney  to 
show  low-grade,  argentiferous  ores  in  depth.  ^ 

2.09.05.  Example  42.  Silver  Islet,  Lake  Superior.  A 
fissure  vein  carrying  native  silver,  argentite,  tetrahedrite, 
galena,  blende,  and  some  nickel  and  cobalt  compounds  in  a 
gangue  of  calcite,  in  flags  and  shales  of  the  Animikie  (Algon- 
kian)  system,  and  cutting  a  large  trap  dike,  within  which 
alone  the  vein  is  productive.  Silver  Islet  is  or  was  originally 
little  more  than  a  bare  rock  some  90  feet  square,  lying  off  the 
north  shore  of  Lake  Superior  just  outside  of  Thunder  Bay,  and 
within  the  Canadian  boundaries.  The  native  silver  was  de- 
tected outcropping  beneath  the  water.  The  vein  was  produc- 
tive to  ^  depth  of  800  or  1,000  feet,  but  below  this  it  yielded  lit- 
tle. The  trap  dike  has  usually  been  called  diorite,  but  is  deter- 
mined to  be  norite  by  Wads  worth  {Bull.  ^,  Minn.  Geol.  Sur- 
vey, p.  92),  and  gabbro  by  Irving  {Monograph  F.,  U.  S.  Geol. 

'  C.  W.  Kempton,  "Sketches  of  the  New  Mining  District  at  Sullivan, 
Me.,"  Trans.  Amer.  Inst.  Min.  Eng.,  VII.,  349.  M.  E.  Wadsworth, 
"Theories  of  Ore  Deposits."  Proc.  Boston  Soc.  Nat.  Hist.,  1884,  p.  205. 
E7ig.  and  Min.  Jour.,  May  17,  1884.  Bull.  Mus.  Camp.  Zodl.,  3,  Vol 
VII.,  181. 

'  T.  B.  Comstock,  Ann.  Rep.  Oeol.  Survey  of  Arkansas,  1888,  Vol.  L, 
"Gold  and  Silver." 


284  KEMP'S  ORE  DEPOSITS. 

Survey,  p.  378).  Some  $3,000,000  were  obtained  from  the 
mine,  yet  the  expenses  were  so  great  in  keeping  up  the  surface 
works  against  winter  gales  and  ice  that  but  little  profit  was 
realized.  The  vein  has  been  traced  9,000  feet,  but  is  nowhere 
else  productive.  Considerable  graphite  has  been  found  in  the 
workings,  and  some  curious  pockets  of  gas.^ 

2.09.06.  Example  42.  Thunder  Bay,  Canada.  The  main- 
land near  Silver  Islet  contains  many  similar  veins.  They  have 
furnished  considerable  silver,  as  argentite  in  a  gangue  of 
quartz,  barite,  calcite  and  fiuorite,  and  associated  with  zinc- 
blende,  galena,  and  pyrite.^ 

THE  REGION  OF  THE  ROCKY  MOUNTAINS  AND  BLACK  HILLS. 

NEW  MEXICO. 

2.09.07.  Geology. — The  general  topography  and  geology  of 
New  Mexico  were  outlined  in  the  introduction.  Much  remains 
to  be  done  in  developing  its  geology.  The  eastern  part  belongs 
to  the  prairie  region,  and  is  very  dry.  A  few  rivers,  notably 
the  Pecos  and  the  Rio  Grande,  afford  water  for  irrigation,  the 
former  of  which  is  now  being  utilized  on  a  grand  scale,  and  for 
the  latter  plans  have  been  prepared.  In  the  central  portion  many 
subordinate  north  arid  south  ranges  of  mountains  are  found, 
which  are  less  elevated  than  those  of  Colorado.  The  Colorado 
ranges  virtually  die  out  at  the  northern  boundary.  The  north- 
western portion  comes  in  the  great  Colorado  plateau,  and  has 
been  quite  fully  described  by  Captain  Button  {Eighth  Ann. 
Rep.  Director  U.  8.  Geol.  Survey).     In  numerous  localities 

^  R.  Bell,  Eng.  and  Min.  Jour.,  January  8  and  15,  1887.  See  also  May 
14,  1887.  W.  M.  Courtis,  ' '  On  Silver  Islet, "  Eng.  and  Min.  Jour. ,  Decem- 
ber 21,  1873,  and  Trans.  Amer.  Inst.  Min.  Eng.,  V..  474.  E.  D.  Ingall, 
Ann.  Rep.  Can.  Geol.  Survey,  1887-88,  Part  II.,  p.  14.  F.  A.  Lowe,  "Tli^ 
Silver  Islet  Mine  and  its  Present  Development,"  Eng.  and  Min.  Jour., 
December  16,  1882,  p.  321.  T.  MacFarlane,  'Silver  Islet,'  Trans.  Amer. 
Inst.  Min.  Eng.,  VIII.,  226.  Geol.  of  Canada,  1863,  717.  Canadian  Nat- 
uralist, Vol.  IV.,  p.  37.  McDermott,  Eng.  and  Min.  Jour.,  Vol.  XXIII., 
Nos.  4  and  5. 

'  R.  Bell,  "Silver  Mines  of  Thunder  Bay,"  Eng.  and  Min.  Jour.,  Jan 
uary  8  and  15,  1887.  E.  D.  Ingall,  Ann.  Rep.  Can.  Survey,  1887-88,  Part 
II.,  p.  IH.  Rec.  See  also  Eng.  and  Min.  Jour.,  May  14,  1887;  February 
18,  1888,  p.  123;  May  26,  1888,  p.  383.  W.  M.  Courtis,  'Animikie  Rocks 
and  their  Vein-phenomena  as  shown  at  the  Duncan  Mine,"  Trans.  Amer, 
Inst.  Min.  Eng.,  XV.,  671;  see  also  V.,  473. 


SILVER  AND  GOLD.  285 

throughout  the  Territory  volcanic  action  has  been  rife,  and  in 
places  is  but  recently  extinct.  The  eastern  part  is  largely  Cre- 
taceous, and  also  the  northwestern  plateau,  which  contains 
much  valuable  coal.  The  mountain  ranges  often  have  nuclei 
of  Archean  crystalline  rocks,  with  successive  strata  of  Carbon- 
iferous, Permian,  Triassic,  Jurassic  and  Cretaceous  on  the 
flanks.  The  mining  regions  are  in  these  ranges  of  mountains.* 
2.09.08.  The  southwestern  county  is  Grant,  whose  lead- 
silver  deposits  have  been  briefly  referred  to.  North  of  Silver 
City  are  quartz  veins  of  gold  and  silver  ores,  in  diabase  and 
quartz  porphyry  (Example  37),  and  again,  west  of 'Silver  City, 
are  ferruginous  deposits  with  chlorides  and  sulphides  of  silver 
in  limestone.  In  the  Burro  Mountains  are  silver  ores  in  lime- 
stones, apparently  Lower  Silurian.  The  Santa  Rita  Mountains 
contain,  in  addition  to  the  copper  (Example  20d),  silver  and 
gold  in  quartz  veins  in  eruptive  rocks  (Example  37).  Lake 
Valley,  in  Dona  Ana  County,  has  been  rjentioned  (2.08.04). 
In  Lincoln  County  gold  ores  are  reported  from  the  White  Oak 
district.     The  principal   mines  of  Socorro   County  have   been 

>  W.  P.  Blake,  Proc.  Bost.  Soc.  Nat.  Hist,  1859,  Vol.  VII.,  p  64.  "Ge- 
ology of  the  Rocky  Mountains  in  the  Vicinity  of  Santa  Fe,"  Amer.  Asso. 
Adv.  Sci.,  1859.  A.  R.  Conkling,  "Report  on  Certain  Foothills  in  North- 
ern New  Mexico,"  Wheeler's  Survey,  Rep.  of  Chief  of  U.  S.  Engineers, 
1877,  II.,  1298.  E.  D.  Cope,  "  Report  on  the  Geology  of  a  Part  of  New 
Mexico,"  Wheeler's  Survey,  1875;  Appendix  Gl.  C.  E.  Button,  "Mount 
Taylor  and  the  Zuni  Plateau,"  Sixth  Ann.  Rep.  U.  S.  Geol.  Survey,  pp. 
111-205.  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  100.  O.  Loew,  "Re- 
port on  the  Geology  and  Mineralogy  of  Colorado  and  New  Mexico.  ' 
Wlieeler's  Survey,  1875;  Appendix  G2,  p.  37.  J.  Marcou,  "The  Mesozoic 
Series  of  New  Mexico,"  Amer.  Geol.,  IV.,  155,  216.  R.  E.  Owen  and  E.  J. 
Cox,  "Report  on  the  Mines  of  New  Mexico,"  Washington,  1865,  60  pp., 
Amer.  Jour.  Sci.,  ii.,  XL.,  391.  G.  F.  Runton,  "On  the  Volcanic  Rocks 
of  New  Mexico,"  Quar.  Jour.  Geol.  Soc,  Vol.  VI.,  p.  251,  1850.  B.  Silli- 
man,  Jr.,  "The  Mineral  Regions  of  Southern  New  Mexico,"  Trans.  Amer. 
Inst.  Min.  Eng.,  X.,  424.  F.  Springer,  "  Occurrence  of  the  Lower  Burling- 
ton Lime.stone  in  New  Mexico,"  Amer.  Jour.  Sci.,  iii.,  XXVII. ,  97.  J.  J. 
Stevenson,  "Geological  Examinations  in  Southern  Colorado  and  North 
em  New  Mexico,"  Wlieeler's  Survey,  1881.  "Geology  of  Gahsteo Creek," 
Amer.  Jotir.  Sci.,  iii.,  XVIII.,  471.  "On  the  Laramie  Group  of  Southern 
New  Mexico,"  Amer.  Jour.  Sci.,  iii.,  XXII.,  370.  For  the  Bibliography  of 
the  Geology  of  the  Territory  in  general,  see  Bulletin  of  the  U.  S.  Geol. 
Survey,  127  (literature  up  through  1891);  130  (1892-1893);  135(1894); 
146  (1895) ;  149  (1896) ;  156  (1897),  and  annual  issues. 


286  KEMP'S  ORE  DEPOSITS. 

mentioned  (Example  29),  and  tbe  copper  in  Permian  sandstone 
under  Example  21c.  There  are  other  silver- bearing  lodes  in 
the  Socorro  Mountains  near  tbe  town  of  Socorro.  Henrich  has 
described  (1.  c.)  a  curious  deposit  of  quartz  carrying  gold  and 
silver  (tbe  Slayback  Lode)  on  the  contact  between  the  older 
bedded  eruptions  and  a  later  siliceous  dike  in  the  Mogollon 
range  (Example  38).  In  Santa  Fe  County  are  important  placer 
mines  (Example  44)  and  thin  veins  of  galena  in  rhyolite.  In 
Bernalillo  County  are  placers  on  the  slopes  of  the  Sandia 
Mountains.  In  Colfax  County,  in  the  Rocky  Mountains,  are 
other  placers,  and  reported  gold  and  silver  mines. ^ 

COLORADO. 

2.09.09.  Geology, — The  eastern  portion  contains  plains 
and  is  a  region  lacking  water.  It  consists  of  Quarternary  and 
Cretaceous  rocks.  The  plains  rise  in  the  foothills,  which  are 
chiefly  upturned  Jura-Triassic  and  Cretaceous  strata.  The 
Paleozoic  is  relatively  limited,  although  known.  It  rests  on 
the  crystalline  rocks  of  the  Archean.  There  are  some  minor 
uplifts,  running  out  at  right  angles  to  the  Front  range,  that 
divide  the  foothill  country  into  basins,  and  are  especially 
important  in  connection  with  coal.  Next  come  the  easterly 
ranges  of  the  Rocky  Mountains,  in  linear  north  and  south 
succession.  They  consist  largely  of  dome-shaped  peaks  of 
granite,  with  great  local  developments  of  volcanic  rocks.  To 
the  west  follow  the  several  parks,  chiefly  consisting  of  Meso- 
zoic  strata.  They  are  bounded  by  ranges  again  on  the  west, 
some  of  which,  like  the  Mosquito  range  (see  under  Example  30), 
mark  great  lines  of  post- Cretaceous  upheaval,  and  are  accom- 
panied by  immense  igneous  intrusions.  On  the  east  and  west 
flanks  of  the  Sawatch  range  (the  granitic  Continental  Divide) 
are  Paleozoic  strata  in  considerable  thickness,  but  to  the  west 

'  W.  P.  Blake,  "Gold  in  New  Mexico,"  Proe.  Post.  Soc.  Nat.  Hist., 
VII.,  p.  16,  July,  1859.  "Observations  on  the  Geology,  etc.,  near  Santa 
Fe,"  Amer.  Asso.  Adv.  of  Sci.,  XIII.,  314,  1860,  S.  F.  Emmons,  Tenth 
Census,  XIII.,  p.  101.  C.  Henrich,  "The  Slayback  Lode,  New  Mexico," 
Eng.  and  Min.  Jour.,  July  13,  1889,  p.  27.  R.  E.  Owen  and  E.  T.  Cox, 
Rep.  on  the  Mines  of  New  Mexico,  Washington,  1865.  Rep.  Director  of  the 
JIfmf,  1883,  p.  339.  B.  Silliman,  "Mineral  Resources  of  Southern  New 
Mexico,"  Trans.  Amer.  Inst.  Min.  Eng.,  X.,  424.  Eng.  and  Min.  Jour., 
October  14  and  21,  1882,  pp.  199,  212. 


SILVER  AND  GOLD.  287 

they  dip  under  the  vastly  greater  development  of  Mesozoic  ter- 
ranes,  which  shade  out  into  the  Colorado  plateau.  In  northern, 
central  and  southwestern  Colorado  are  vast  developments  of 
igneous  rocks  that  have  attended  the  geological  disturbances/ 
2.09.10.  The  San  Juan  region  includes  several  counties  in 
southwestern  Colorado,  in  whole  or  in  part,  viz. :  Ouray,  Hins- 
dale, San  Juan,  Dolores,  and  La  Plata.  The  chain  of  the  San 
Juan  Mountains  consists  of  great  successive  outflows  of  erup- 
tive rocks,  andesite,  diabase,  diorite,  basalt,  etc.,  which  cover 
up  the  Archean  and  later  sedimentary  terranes,  except  in  a 
few  scattered  exposures.  Considerable  masses  of  rocks  formed 
of  fragmental  ejectamenta  are  also  known.  All  these  are  crossed 
by  immense  vertical  veins,  largely  with  quartz  gangue,  and  con-, 
taining  argentiferous  minerals  of  the  usual  species,  galena, 
tetrahedrite,  pyrargerite,  and  native  silver,  as  well  as  bismuth 
compounds.  Gold  has  been  quite  subordinate,  although  late 
developments  near  Ouray  have  shown  some  peculiar  and  inter- 
esting deposits.  R.  C.  Hills,  as  quoted  by  S.  F.  Emmons,  1885, 
traced  three  systems  of  veins.  (1)  Silver  bearing,  narrow  (six 
inches  to  three  feet),  nearly  vertical  veins,  with  base  metal  ores 

*  G.  L.  Gannon,  "Quaternary  of  the  Denver  Basin,"  Proc.  Colo.  Sci. 
Sac.,  III.,  48.  See  also  III.,  200.  "Geology  of  Denver  and  Vicinity," 
Idem,  IV.,  235.  Rec.  W.  Cross,  "The  Denver  Tertiary  Formation," 
Amer.  Jour.  Sci.,  iii.,  XXXVII.,  261."  "Pike's  Peak,"  Atlas  Folio, 
U  S.  Geol .  Survey,  No.  7.  Rec.  ' '  On  a  Series  of  Peculiar  Schists  near 
Salida,"  Proc.  Colo,  Sci.  Soc,  IV.,  286.  Rec.  "The  Laccolitic  Mtn. 
Groups  of  Colorado,  Utah  and  Arizona,"  Ann.  Rep.  Dir.  U.  S.  Geol.  Sur- 
vey, XIV.,  165.  Rec.  G.  H.  Eldredge,  "On  the  Country  about  Denver, 
Colo.,"  Proc.  Colo.  Sci.  Soc,  III.,  88.  See  also  140.  S.  F.  Eminons, 
"  Orographic  Movements  in  the  Rocky  Mountains, "  Geol.  Soc.  of  America, 
I.,  245-286.  F.  M.  Endlich,  "On  the  Eruptive  Rocks  of  Colorado,"  Tenth 
Ann.  Rep.,  Hayden's  Survey.  H.  Gannett,  "Report  on  the  Arable  and 
Pasture  Lands  of  Colorado,"  Hayden's  Survey,  1876,  p.  313.  H.  C.  Free- 
man, "The  La  Plata  Mountains,"  Trans.  Amer.  Inst.  Min.  Eng.,  XIII, 
681.  G.  K.  Gilbert,  "Colorado  Plateau  Province  as  a  Field  for  Geological 
Study, "  Amer.  Jour.  Sci. ,  iii. ,  XII. ,  16,  85.  J.  D.  Hague,  Fortieth  Paral- 
lel Survey,  Vol.  HI.,  p.  475.  F.  V.  Hayden,  Reps,  of  Hayden's  Survey, 
1873,  1874,  p.  40;  1875,  p.  33;  1876,  pft  5,  70.  R.  C.  Hills,  "Preliminary 
Notes  on  the  Eruptions  of  the  Spanish  Peaks,"  Proc.  Colo.  Sci.  Soc.  III., 
34,  224.  "The  Recently  Discovered  Tertiary  Beds  of  the  Huerfano  River 
Basin,"  Proc  Colo.  Sci.  Soc,  III.,  pp.  148,  217.  "Jura  Trias  of  South- 
eastern Colorado,"  Amer.  Jour.  Sci.,  iii.,  XXIII.,  p.  243.  "Orographic 
and  Structural  Features  of  Rocky  Mountain  Geology,"  Proc.  Colo.  Sci 


288  KEMP'S  ORE  DEPOSITS. 

and  no  selvage.  (2)  Large,  strong,  gold-bearing  veins  dipping 
60°  with  selvages  and  intersecting  (1).  (3)  Like  (l),  but  larger 
and  more  persistent,  and  carrying  occasional  bismuth  and  anti- 
monial  ores  with  gold  and  little  or  no  silver.  T.  B.  Comstock 
{Tr^ns,  Amer.  Inst.  Min.  Eng.,  XV.,  218)  has  classified  the 
veins  in  three  radiating  systems.  (1)  The  northwest,  with 
tetrahedrite  (freibergite).  (2)  The  east  and  west,  with  bismuth 
and  less  often  nickel  and  molybdenum.  (3)  The  northeast, 
with  tellurides  and  antimon)^  and  sulphur  compounds  of  the 
precious  metals.  Quite  recently  a  series  of  small  caves  near 
Ouray,  in  quartzite  overlaid  by  bituminous  shales  have  been 
found  to  contain  native  gold,  and  have  excited  great  interest. 
It  is  thought  by  Endlich  that  they  represent  inclusions  of 
shale,  now  dissolved  away,  and  that  the  gold  was  precipitated 
on  the  walls.  If  this  view  is  correct,  they  mark  one  of  the 
very  few  illustrations  of  chamber  deposits  which  are  known. 
More  extended  mining  work  has  proved  them  to  be  in  all  cases 
connected  with  a  supply  fissure  from  which  small  leaders  guide 
the  miners  to  the  chambers. 

In  the  vicinity  of  Telluride  there  is  a  very  interesting  devel- 
opment of  veins.     One  of  the  most  remarkable  and  persistent 

Soc. ,  III.,  363.  Rec.  ' '  Types  of  Past  Eruptions  in  the  Rocky  Mountains," 
Idem,  IV.,  14.  Rec.  A.  Lakes,  "  Extinct  Volcanoes  in  Colorado,"  ^mer. 
Geol.,  January,  1890,  p.  38.  Oscar  Loew,  "Report  on  the  Minerals  of 
Colorado  and  New  Mexico,"  Wheeler's  Survey,  1875,  p.  97.  "Eruptive 
Rocks  of  Colorado,"  Wheeler's  Survey,  1873.  C.  A.  H.  McCauley,  "On 
the  San  Juan  Region,"  Rep.  Chief  of  U.  S.  Engineers,  1878,  III.,  p.  1753. 
C.  S^  Palmer,  "On  the  Eruptive  Rocks  of  Boulder  County,"  etc.,  Proc. 
Colo.  Sci.  Soc,  III.,  p.  230.  A.  C.  Peale,  "On  the  Age  of  the  Rocky 
Mountains  in  Colorado,"  Amer.  Jour.  Sci.,  in.,  XIII.,  p.  172;  Reply  to  the 
above  by  J.  J.  Stevenson,  Amer.  Jour.  Sci.,  iii.,  XIII.,  297.  T.  A.  Rick- 
ard,  "Gold  Resources  of  Colorado,"  The  Mineral  Industry,  II.,  325;  IV., 
315.  S.  H.  Scudder,  "The  Tertiary  Lake  Basin  at  Florissant,"  Hayden's 
Survey,  1878,  p.  271 ;  see  also  1877.  J.  A.  Smith,  Catalogue  of  the  Princi- 
pal Minerals  of  Colorado,  Central  City,  1870.  J.  J.  Stevenson,  "  Notes  on 
the  Laramie  Group  of  Southern  Colorado,"  Amer.  Jour.  Sci.,  iii.,  XVIII. 
129.  "TheMesozoic  Rocks  of  Southern  Colorado,"  ^mer.  Geol.,  III.,  p, 
391.  P.  H.  Van  Diest,  "  Colorado  Volcanic  Cones,"  Proc.  Colo.  Sci.  Soc. 
III.,  p.  19.  C.  A.  White,  "On  Northwestern  Colorado,"  Ninth  Ann.  Rep 
Director  U.  S.  Geol.  Survey,  683-710.  For  the  complete  geological  bibli 
ography  of  the  State,  see  Bulletins  U.  S.  Geol.  Survey,  127  (1732-1891) ;  130 
(1892-93);  185  (1894);  146  (1895);  149  (1896);  156  (1897),  and  current 
annuals. 


SILVER  AND   GOLD. 


289 


is  the   Smuggler,  recently   described    by  J.  A.  Porter.     It    is 
known  for  a  stretch  of  four  miles  and  cuts  the  high  divide  that 


Not  Classified 

' 

Rhyolites  and 
Andesites 

as  to           < 

Geologic  Age. 

2 

"~[    S«n  Juan  Formation 
_J      Andesitic  Breccia 

Shales  and 
SandstonM. 


Fig.  102. — Geological  sketch-map  of  tlie  Telluride  district,  Colorado.     Ajter 
Arthur  Winslow,  Trans.  Amer.  Inst.  Min.  Eng.,  February,  1899, 

separates  the  Marshall  basin  near  the  town  of  Telluride,  on 
the  south,  in  the  drainage  area  of  the  San  Miguel  River,  from 


290  KEMP'S  ORE  DEPOSITS. 

the  valleys  of  Canon  Creek,  a  tributary  of  the  Uncompahgre 
River,  that  lies  to  the  north.  (See  Fig.  102.)  The  summit  of 
the  'divide  is  13,200  feet  above  tide.  Whitman  Cross  has  been 
mapping  an  atlas  sheet  for  the  U.  S.  Geological  Survey  in  the 
vicinity  of  Telluride,  and  has  prepared  in  advance  of  its  issue 
a  sketch  of  the  local  geology.  (**  The  San  Miguel  Formation, 
Igneous  Rocks  of  the  Telluride  District,'^  Proc.  Colo.  Sci.  Soc, 
September,  1896.)  The  formations  of  interest  in  connection  with 
the  vein,  begin  with  the  San  Miguel  conglomerate,  which  is 
probably  of  closiug  Cretaceous  or  early  Eocene  age.  On  this 
is  the  San  Juan  formation,  2,000  feet  thick,  of  bedded  volcanic 
andesitic  tuffs,  the  chief  wall  rocks.  Above  follow  sheets  of 
various  andesites  and  rhyolites,  which  are  cut  by  the  highest 
parts  of  the  vein.  The  fissure  containing  the  ore  body  has  cut 
this  series  and  is  known  for  3,500  feet  vertically,  but  what  its 
character  is  in  the  San  Miguel  conglomerate  is  not  yet  demon- 
strated. The  gangue  is  chiefly  quartz,  with  some  rhodochrosite, 
calcite,  siderite  and  barite.  The  values  in  silver  are  highest  at 
the  north,  and  yield  to  gold  values  to  the  south.  Two  other 
notable  veins  cross  and  fault  the  Smuggler,  one  the  Pandora, 
containing  auriferous  quartz,  the  other  the  Revenue,  with  con- 
siderable lead.  So  constant  is  the  character  of  the  Smuggler 
thatstoping  ground  has  been  broken  for  a  mile  without  a  break. 
(J.  A.  Porter,  **The  Smuggler-Union  Mines,  Telluride,  Colo.,'» 
Trans.  Amer.  Inst,  Min.  Eng.,  XXVI.,  449.)  The  region  is 
indeed  one  of  remarkably  persistent  and  clear-cut  fissures,^ 
which  are  shown  on  Fig.  102. 

Placer  gold  mines  (Example  44)  are  quite  extensively 
worked  in  San  Miguel  County.  J.  B.  Farish  has  de- 
scribed the  veins  at  Newman  Hill,  near  Rico,  in  a  valuable 
paper  cited  below.  The  lowest  formation  exposed  is  magnesian 
limestone,  supposed  to  be  Carboniferous.  It  contains  large  ore 
bodies  of  low  grade,  and  is  also,  strangely  enough,  heavily 
charged  with  carbonic  acid  gas.  Above  this  for  500  feet  are 
alternating  sandstones  and  shales,  and  then  a  narrow  stratum 
of  limestone  18  to  30  inches  thick.     This  is  followed  by  about 

*  C.  W.  Purington,  "  Preliminary  Report  on  the  Mining  Industries  of 
the  Telluride  Quadrangle,"  Eighteenth  Ann.  Rep.  Director  U.  S.  Geol. 
Survey.  Arthur  Winslow,  "  The  Liberty  Bell  Gold  Mine,  Telluride,  Colo- 
rado," Trans.  Amer.  Inst.  Min.  Eng.,  Febiniary,  1899. 


SILVER  AND  GOLD. 


291 


292  KEMP'S  ORE  DEPOSITS. 

500  feet  additional  of  shales  and  sandstone,  regarded  as  Car- 
boniferous. Fifty  feet  above  the  lowest  limestone  a  laccolite 
of  porpbyrite  has  been  intruded.  Two  sets  of  fissures  are  pres- 
ent—one nearly  vertical  and  striking  northeast,  the  second  dip- 
ping 30  to  45°  northeast,  and  striking  northwest.  The  former 
are  the  richest,  are  rudely  banded  and  persistent,  being  worked 
in  one  case  for  4,000  feet.  The  flatter  fissures  are  less  rich. 
The  principal  ore  bodies,  however,  occur  as  horizontal  enlarge- 
ments of  both  these  sets  of  veins.  Just  over  the  thin  bed  of 
limestone  mentioned  above  the  ores  have  spread  out  into  sheets 
from  20  to  40  feet  wide,  and  from  a  few  inches  to  three  feet 
thick.  They  consist  of  solid  masses  of  the  common  sulphides, 
galena,  pyrite,  gray  copper,  etc.,  and  are   very   rich.     Above 


Fig.  104. — Geological  cross  sections  of  strata  and  veins  at  Newman  Hill,  ne(Mf 

Rico,  Colo.     After  J.  B.  Farish,  Proc.  Colo.  Sci.  Soc, 

April  4,  1892.     See  also  Figures  5  and  6. 

them  the  fissures  apparently  cease,  or  at  least  are  tight.  Two 
hundred  feet  down  from  them  the  vein  filling  becomes  nearly 
barren,  glassy  quartz.  These  are  most  remarkable  ore  bodies, 
and  would  appear  to  have  been  formed  by  uprising  solutions, 
which  met  the  tight  place  and  spread  sidewise,  depositing  their 
minerals;  but  as  Mr.  Farish  advances  no  explanation,  it  is 
hardly  justifiable  for  others,  less  familiar  than  himself  with 
the  phenomena,  to  do  so.  T.  A.  Kickard  has  also  written  of 
them,  and  has  illustrated  the  details  of  vein  structure  in  a  verj^ 
significant  series  of  plates,  which  show  the  banding  to  be  ir- 
regular and  not  persistent.  He  has  also  introduced  some  cor- 
rected interpretations  of  the  faults. 

The  lead-silver  ores  of  Red  Mountain  and   Rico  have  al- 


SILVER  AND  GOLD.  293 

ready  been  mentioned  (2.08.17).     Silverton  and  Ouray  are  the 
principal  towns  of  the  San  Juan.^ 

2.09.11.  The  new  mining  region  of  Creede,  now  decided  to 
be  in  Saguache  County,  should  be  mentioned  in  this  connec- 
tion. It  is  situated  near  the  junction  of  Saguache,  Ouray  and 
Hinsdale  counties,  and  some  ten  or  twelve  miles  from  Wagon 
Wheel  Gap.  There  is  a  great  development  of  igneous  rocks 
as  well  as  of  Carboniferous  limestone,  but  the  veins  as  yet  devel- 
oped are  in  the  former.  They  appear  to  be  fissure  veins,  and 
have  quartz,  in  large  part  amethyst,  with  some  manganese 
minerals  as  a  gangue,  and,  with  these,  oxidized  silver  ores.  The 
mines  are  on  two  mountains.  Bachelor  and  Campbell,  which 
are  on  opposite  sides  of  Willow  Creek  Canon. ^ 

*  T.  B.  Comstock,  "The  Geology  and  Vein  Structure  of  Southwestern 
Colorado,"  Trans.  Amer.  Inst.  Min.  Eng.,  Vol.  XV.,  218;  also  XI.,  165,  and 
Eng.  and  Min.  Jour.,  numerous  papers  in  1885.     "  Hot  Spring  Formation 
Iftin  the  Red  Mountain  District,  Colorado,"  Trans.  Amer.  Inst.  Min.  Eng., 
XVII.,    261.    S.    F.    Emmons,    "On    the  San  Juan  District,"  E7ig.  and 
Min.  Jour.,  June  9,  1883,  p.  332.     "Structural  Relations  of  Ore  Deposits," 
Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  804.     Rec.     Tenth  Census,  Vol.  XIII., 
p.  60.     F.  M.  Endlich,  "Origin  of  the  Gold  Deposits  near  Ouray,"  Eng.  and 
Min.  Jour. ,  October  19,  1889.     ' '  San  Juan  District, "  Hayden's  Survey,  1874, 
p.  229.     Ibid.,  1875,  Bull.  Ill,  Amer.  Jour.  Sci.,  iii.,  X.,  58.     J.  B.  Farish, 
"On  the  Ore  Deposits  of  Newman  Hill,  near  Rico,  Colo.,"  Colo.  Sci.  Soc, 
April 4,  1892.    Rec.    W.  H.  Holmes,  "La  Plata  District,"  Hayden's Survey, 
1875;  Amer.  Jour.  Sci.,   iii.,  XIV.,  420.     M.  C.  Ihlseng,  "Review   of  the 
Mining  Interests  of  the  San  Juan  Region,"  Rep.  Colo.  State  School  of 
Mines,    1885,  p.  27.     G.  E.  Kedzie,   "The  Bedded  Ore  Deposits  of  Red 
Mountain  Mining  District,  Ouray  County,  Colorado,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XV.,  570.    Rec.    G.  A.  Koenig  and  M.  Stocker,  "Lustrous  Coal 
and  Native  Silver  in  a  Vein  in  Porphyry,  Ouray  County,  Colorado,"   Trans. 
Amer.  Inst.  Min.  Eng.,  IX.,  650.     T.  A.  Rickard,  "Vein  Structure  in  the 
Enterprise  Mine."  Proc.    Colo.    Sci.    Soc,    Adv.    Sheets,    Vol.  V.     T.  E. 
Schwartz,  "The  Ore  Deposits  of  Red  Mountain,  Ouray  County,  Colorado," 
Trans.  Amer.  Inst.  Min.  Eng.,   XVIII.,  139,  1889.     J.   J.  Stevenson,  "On 
the  San  Juan,"  Wheeler's  Survey,  HI.,  p.  376.     "The  San  Juan  Region," 
Eng.  and  Min.  Jour.,  August  27,  1881,  p.  136;  September  24,  1881,  p.  201; 
July  17,  1880;  December  20,  1879;  and  many  other  references  in  1879  and 
1880.     P.  H.  Van  Diest,  "Notes  on  a  Trip  to  Telluride,  San  Miguel  Co., 
Colo.,"  Proc.  Colo.  Sci.  Soc,  II.,  28,  1885;  Idem,  January,  1886. 

'  E.  B.  Kirby,  "The  Ore  Deposits  of  Creede  and  their  Possibilities," 
Eng.  and.  Min.  Jour.,  March  19,  1892,  p.  325.  Rec.  T.  R.  MacMechen, 
"7 he  Ore  Deposits  of  Creede,"  Eng.  and  Min.  Jour.,  March  12,  1892,  p 
301.     Rec. 


394  KEMP'S  ORE  DEPOSITS. 

2. 09. 12 .  The  Gunnison  region  lies  on  the  western  slope  of  the 
Continental  Divide,  and  embraces  both  mountains  and  pla- 
teaus. West  of  the  main  and  older  range  are  the  later  Elk 
Mountains,  in  which  several  mining  districts  are  located. 
Aspen  ha^  already  been  mentioned,  and  the  long  series  of  ore 
bodies  in  the  Carboniferous  limestones.  The  other  principal 
districts  are  Independence,  Ruby,  Gothic,  Pitkin  and  Tin 
Cup.  The  ores  at  Independence  are  sulphides  with  silver,  in 
the  Archean  granite  rocks.  In  the  Tin  Cup  district  the  Gold 
Cup  mine  is  in  a  black  limestone  and  contains  argentiferous 
cerussite  and  copper  oxide.  In  the  Ruby  district  the  ores  are 
in  the  Cretaceous  rocks,  and  in  the  Forest  Queen  they  are  ruby 
silver  and  arsenopyrite,  partly  replacing  a  porphyry  dike.  On 
Copper  Creek,  near  Gothic,  a  series  of  nearly  vertical  fissures 
traverse  eruptive  diorite.  They  contain  sulphide  of  silver  and 
native  silver.  The  Sylvanite  is  one  of  the  principal  mines. 
Arthur  Lakes  has  described  some  very  curious  veins  in 
Gunnison  Co.,  the  Yulcan  and  Mammoth,  that  contain  opalineit 
silica  and  native  sulphur  together  with  pyrites.^ 

2.09.13.  Eagle  County.  The  lead-silver  mines  of  Red  Cliff 
have  already  been  mentioned  (Example  30c),  and  also  the 
underlying  gold  deposits.  The  Homestake  mine,  northwest  of 
Leadville,  over  toward  Red  Cliff,  is  on  a  vein  of  galena  in 
granite,  and  was  one  of  the  first  openings  made  in  the  region.^ 

2.09.14.  Summit  County.  The  Ten-Mile  district,  which  is 
the  principal  one,  has  been  mentioned  under  Example  30a. 
Lake  County,  containing  Leadville,  has  been  treated  under 
Example  30.    Mention  should  also  be  made  of  the  placer  depos- 

^  F.  Amelung,  "  Sheep  Mountain  Mines,  Gunnison  County,  Colo.,"  Eng. 
andMin.  Jour.,  August  28, 1886,  p.  149.  F.  M.  Chadwick,  "The  Tin  Cup 
Mines,  Gunnison  County,  Colorado,"  Eng.  and  Min.  Jour.,  January  1, 
1881,  p.  4.  See  also  Example  12d  for  iron  mines.  J.  R.  Holibaugh, 
"Gold  Belt  of  Pitkin,  Gunnison  Co.,  Colo.,'' Eng.  and  Min.  Jour.,  Decem- 
ber 12,  1896,  p.  559.  Arthur  Lakes,  "Sketch  of  a  Portion  of  the  Gunni- 
son Gold  Belt,"  etc..  Trans.  Amer.  Inst.  Min.  Eng.,  XXVI.,  440. 

«  F.  Guiterman,  "On  the  Gold  Deposits  of  Red  Cliff,"  Proc.  Colo.  Set. 
Sac.,  1890.  "On  the  Battle  Mountain  Quartzite  Mines,"  Mining hidustry, 
Denver,  January  10,  1890,  p.  28.  E.  E.  Olcott,  "Battle  Mountain  Mining 
District,  Eagle  County,"  Eng.  and  Min.  Jour.,  June  11  and  18,  1887,  pp. 
417,  436;  May  21,  1892.  G.  C.  Tilden,  "Mining  Notes  from  Eagle  County," 
Ann.  Rep.  Colo.  State  School  of  Mines,  1886,  p.  129. 


SILVER  AND  GOLD.  295 

its  in  California  Gulch,  which  first  attracted  prospectors  to  the 
region  in  1860.  In  its  eastern  part  Summit  County  borders  on 
Clear  Creek  County,  and  at  Argentine  are  some  veins  related 
to  those  of  the  latter.  They  are  high  up  on  Mount  McClellan, 
and  are  remarkable  for  the  veins  of  ice  that  are  found  in  them.^ 

2.09.15.  Park  County,  which  lies  east  of  Lake  County  and 
embraces  the  South  Park,  has  some  mines  on  the  eastern  slope 
of  the  Mosquito  range,  and  in  the  Colorado  range,  to  the  north- 
west. The  latter  are  similar  in  their  contents  to  the  George- 
town silver  ores,  mentioned  under  Clear  Creek  County,  but  the 
former  are  bodies  of  argentiferous  galena  and  its  alteration 
products  in  limestone  and  quartzite.  Pyrite  is  also  abundant, 
and  at  times  a  gangue  of  barite  appears.  The  mines  are  in  the 
sedimentary  series,  resting  on  the  granite  of  the  Mosquito 
range,  and  are  pierced  by  porphyry  intrusions,  as  at  Leadville. 
The  placer  deposits  at  Fairplay  deserve  mention,  as  it  was 
from  these  that  the  prospectors  spread  over  the  divide  to  the  site 
of  Leadville  in  I860.' 

2.09.16.  Chaffee  County,  on  the  south,  contains  the  iron 
mines  referred  to  under  Example  12d.  There  are  some  other 
gold-bearing  veins  near  Granite  and  Buena  Vista.  The  lead- 
silver  deposits  of  the  Monarch  district  are  mentioned  under 
Example  306.  In  Huerfano  County,  in  the  Spanish  Peaks, 
veins  of  galena,  gray  copper,  etc.,  are  worked  to  some  ex- 
tent.' 

2.09.17.  Rio  Grande  County.  In  the  Summit  district  are 
a  number  of  rich  gold  mines,  of  which  the  Little  Annie  is  the 
best  known.  The  gold  occurs  in  the  native  state,  in  quartz 
on  the  contact  between  a  rhyolite  and  trachyte  breccia  and 
andesite.  The  deposits  are  thought  by  R.  C.  Hills  to  be  due  to 
a  silicificationof  the  rhyolite  along  those  lines,  probably  by  the 
sulphuric  acid,  which  brought  the  gold.  Then  the  rocks  were 
folded.  Oxidation  and  impoverishment  of  the  upper  parts  fol- 
_— _. I        

^  E.  L.  Berthoud,  ' '  On  Rifts  of  Ice  in  the  Rocks  near  the  Summit  of 
Mount  McClellan,"  etc.,  Amer.  Jour.  Set.,  iii.,  II.,  108.  Ten-Mile  Special 
Folio,  U.  S.  Geol.  Survey,  by  S.  F.  Emmons.     Rec. 

"  J.  L.  Jernegan,  "Whale  Lode  of  Park  County,"  Trans.  Amer.  Inst. 
Min.  Eng.,  III.,  352. 

'  R.  C.  Hills,  "  On  the  Eruption  of  the  Spanish  Peaks,"  Proc.  Colo.  Sci. 
Soc,  III.,  pp.  24,  224. 


296  KEMP'S  ORE  DEPOSITS. 

lowed,  forming  bonanzas  below.     The  paper  has  a  very  impor- 
tant bearing  on  the  formation  of  manj^  replacements.^ 

2.09.18.  Conejos  County.  Some  deposits  of  ruby  silver 
ores  have  recently  been  developed  in  this  county,  near  the 
town  of  Platoro.  The  county  lies  near  the  middle  of  the  south- 
ern tier. 

2.09.19.  Custer  County  affords  some  of  the  most  interesting 
deposits  in  the  West.  Rosita  and  Silver  Cliff  are  the  principal 
towns,  and  are  situated  in  the  Wet  Mountain  Valley,  between 
the  Colorado  range  on  the  north  and  the  Sangre  de  Cristo  on 
the  south.  In  the  northern  portion  of  the  area  immediately 
concerned  with  the  mines  gneisses  of  undetermined  but  proba- 
bly very  ancient  age  outcrop,  which,  to  the  south,  are  buried 
beneath  an  extensive  development  of  igneous  (mostly  volcanic) 
rocks,  and  Pleistocene  gravels,  alluvium  and  lake  beds.  The 
igneous  rocks  embrace  rhyolite,  trachyte,  dacite,  three  varie- 
ties of  andesite,  diorite,  agglomerate  and  tuffs.  The  volcanic 
rocks  were  derived  from  outbreaks  that  took  place  during  the 
Eocene,  as  nearly  as  can  be  determined  by  some  fossil  leaves 
which  are  buried  in  the  tuffs.  It  is  interesting  to  note  that  the 
Cripple  Creek  volcanic  center  lies  about  40  miles  north.  The 
volcanic  rocks  are  chiefly  represented  in  the  Rosita  Hills  near 
the  town  of  the  same  name,  and  in  the  flow  of  rhyolite  north 
of  Silver  Cliff.  In  addition  to  the  volcanics  there  are  syenite, 
granite  and  diabase  in  the  gneisses.  Several  different  forms 
of  ore  body  have  been  developed,  each  of  which  possesses  excep- 
tional claims  to  interest,  and  one  of  which  forms  a  quite  unique 
type,  at  least,  so  far  as  American  experience  has  yet  gone. 

2.09.20.  Example  39.  The  Bassick  Mine.  An  explosive 
volcano  seems  to  have  broken  out  at  the  situation  of  the  Bas- 
sick mine,  and  to  have  produced  an  elliptical  pipe  or  conduit 
about  1,500x1,000  feet  in  the  fundamental  gneiss  of  the  dis- 
trict, and  to  have  subsided,  leaving  the  tube  filled  with 
rounded  boulders,  which  are  chiefly  andesite,  but  which  em- 
brace also  granite,  gneiss  and  even  carbonized  wood.  A  small 
dike  of  basaltic  rock  (limburgite)  is  also  known  to  be  present. 
A  portion  of  the  agglomerate  in  the  shape  of  one  and  perhaps 
more,  nearly  vertical  pipes  or  chimneys,  has  been  impregnated 

»  R.  C.  Hills,  Proe.  Colo.  Sci.  Soc,   March,   1883.     Abstract  by  S.  F. 
Emmons  in  the  Eng.  and  Min.  Jour.,  June  9.  1883,  p.  332. 


SILVER  AND   GOLD.  297 

with  rich  ores  of  gold  and  silver,  which  coat  the  rounded  boul- 
ders in  successive  shells  of  metallic  minerals.  The  first  coat  is 
a  mixture  of  lead,  antimony  and  zinc  sulphides,  and  is  alwaj^s 
present.  A  second,  somewhat  similar,  but  of  lighter  color  and 
richer  in  lead  and  the  precious  metals,  is  sometimes  seen.  A 
third  is  chiefly  zincblende,  rich  in  silver  and  gold,  and  is  the 
largest  of  all.  A  fourth,  of  chalcopyrite,  sometimes  occurs, 
and  lastly,  a  fifth,  of  pyrite.  Some  lots  of  ore  also  yielded  rich 
tellurides  of  the  precious  metals.  On  the  Bassick  chimney  the 
workings  have  gone  to  1,400  feet  in  depth,  without  losing  the 
ore,  which  was  roughly  elliptical  and  100x20  to  30  feet.  From 
the  seventh  level  downward  cross-cuts  opened  up  a  second 
chimney  lying  150  feet  east.  The  Bassick  has  been  considered 
by  the  earlier  observers  to  be  a  geyser  tube  in  which  the  bowl- 
ders were  tossed  about,  rounded  and  coated  with  ore.  Whit- 
man Cross  has,  however,  satisfactorily  demonstrated  the  exist- 
ence of  the  agglomerate,  and  S.  F.  Emmons  has  reached  the 
conclusion  that  the  ores  have  come  in  through  fissures  which 
can  be  detected  in  the  mine.  At  the  intersection  of  two  which 
cross  each  other,  the  chief  ore  body  has  been  found.  The  ores 
are  of  such  a  nature  that  Emmons  regards  their  introduction 
in  the  form  of  vapors  as  possible,  although  at  depths  these 
vapors  were  probably  confined  in  the  liquid  state.  The  ores 
would  then  befumarolic  impregnations  which  have  replaced  the 
interstitial  filling  of  the  agglomerate. 

Example  39a.  The  Bull  Domingo  Mine.  The  Bull  Do- 
mingo lies  north  of  Silver  Cliff  and  some  miles  northwest  from 
the  Bassick.  The  country  rock  is  the  ancient  gneiss,  but  near 
the  mine  dikes  of  granite  and  syenite  are  known.  The  ore  was 
found  in  an  elliptical  chimney,  of  variable  size,  but  at  the  150 
foot  level,  90x40  feet.  It  has  been  exploited  down  to  the  550 
level.  The  ore  consists  of  rounded  boulders  of  gneiss,  syenite 
and  granite,  which  are  coated  with  successive  shells  of  coarsely 
crystalline  galena,  somewhat  fibrous  zincblende,  and  specks  of 
pyrite.  Outside  these  are  in  order  shells  of  white  dolomite, 
ankerite  or  siderite,  calcite,  and  chalcedony.  There  is  abun- 
dant evidence  of  extensive  fracturing  of  the  rocks  at  the  mine, 
and  the  evidence  points,  according  to  S.  F.  Emmons,  rather  to 
a  shattered  mass  of  country  rock,  whose  brecciated  fragments 
have   been  rounded,  replaced  and  coated  with  ore  b}'  uprising 


298 


KEMP'S  ORE  DEPOSITS. 


solutions,  than  to  an  explosive  volcanic  outbreak  or  geyser,  as 
had  been  previously  thought.  The  general  similarity  in  struct- 
ure of  the  ore  to  that  of  the  Bassick  suggested  quite  naturally 
a  similar  origin  to  the  earlier  observers.     It  is  interesting  to 


Hew  Shaft      Old  Shaft 


Fig.  105. 


Fig.  106. 


Fig.  105. — Cross  section  of  the  Bassic  Mine,  near  Rosita.  After  S.  F.  Emmons, 

XV IL  Ann.  Rep.  U.  8.  Oeol.  Survey,  Part  11. ,  p.  434. 

Fig.  106. — Cross  section  of  the  Bull- Domingo  Mine,  near  Silver  Cliff,  Colo. 

After  S.  F.  Emmons,  X  VIL  Ann.  Rep.  U.  S.  Ceol.  Survey, 

Part  II. ,  p.  442. 


compare  the  two  chimneys  of  the  Bassick  and  Bull  Domingo 
with  that  of  the  Annie  Lee  at  Victor  in  the  Cripi^le  Creek 
district      Specimens  and  notes  given  the  writer  by  E.  J.  Chibas 


SILVER  AND  OOLD. 


299 


would  indicate  a  similar  deposit  at  the  mines  of  the  Darien 
Gold  Mining  Company,  Cana,  Columbia.  (See  also  E.  R. 
Woakes,  Amer.  Inst.  Min.  Eng.,  Atlantic  Cit}'  meeting,  Feb- 
ruary, 1898.) 

2.09.21.  Humboldt-Pocahontas.  This  vein  is  one  of  sev- 
eral which  have  been  discovered  near  Rosita.  It  is  a  fissure 
vein  which  cut  in  its  upper  portion  a  mass  of  andesite  and 
andesite  breccia,  but  which  at  the  fourth  level,  as  shown  in 
Fig.  107,  forked  into  several  feeders.  Above  this  point  it  was 
one  of  the  most  regular  and  clear-cut  fissures  ever  mined  in 
the  West.     The  ore  was  tetrahedrite  in  a  gangue  of  barite  and 


^Ml      1^!^ 


ROSITA 
AT^DESITE 


TRACHYTE 
-PORPHYRY 


GRANITE 


BROKEN  ZONE 

OF  PORPHYRY 

&  ANDESITE 

Fig.  107. — Cross  section  of  the  Humboldt- Pocahontas  vein,  near  Rosita,  Colo. 

After  8.  F.  Emmons,  XVIL  Ann.  Rep.  U.  S.  Ueol.  Survey, 

Part  11.,  V-  437 


decomposed  wall  rock,  with  which  were  associated  chalcopy- 
rite,  pyrite,  galena  and  antimonial  sulphides  of  silver.  In  the 
lower  levels  the  vein  broke  up  into  several  small  fissures  and 
troubles,  such  that  operations  ceased. 

2.09.22.  Silver  Cliff.  At  Silver  Cliff  there  is  a  large  flow 
of  porous  rhyolite  just  north  of  the  town,  which  was  early 
found  to  be  impregnated  along  small  fissures,  with  chloride  of 
silver  and  black  manganese  minerals.  For  a  time  free-mill- 
ing ore  was  quarried.  Later  a  deep  shaft  was  sunk  in  the  Gey- 
ser mine,  which  at  1,850  feet  found  the  faulted  contact  with  the 


300  KEMP'S  ORE  DEPOSITS. 

Archean  gneiss  and  200  out  into  the  rhyolitic  tuff  a  cross-cut 
encountered  a  vein  that  proved  productive  of  rich  silver  ore. 
This  deep  shaft  afforded  some  interesting  samples  of  deep  and 
vados©  waters,  which  have  been  analyzed  by  W.  H.  Hille- 
brand,  as  given  in  Emmons'  paper  (see  above  p.  31).  The 
rhyolite  also  afforded  in  the  surface  workings  some  extraordi- 
narily large  spherulites  which  have  been  described  by  Cross. 
Assays  of  fresh  and  unaltered  samples  of  the  country  rocks, 
which  were  made  for  S.  F.  Emmons,  indicated  the  presence  of 
silver  in  five  out  of  nine,  viz. :  trachyte,  0.007  oz.  per  ton;  Fair- 
view  diorite,  0.01  oz.  per  ton;  rhyolite,  0.402  oz.  per  ton;  red 
granite,  0.005  oz.  per  ton;  black  granite,  0.025  oz.  per  ton; 
bisilicates  of  the  granite,  0.04  oz.  silver  per  ton,  and  0.045  per 
cent,  lead.^ 

2.09.24.  Teller  County.  The  region  of  Cripple  Creek  is  the 
only  one  of  serious  importance  in  this  county,  but  the  remarka- 
ble developments  of  the  last  few  years  have  placed  it  in  a  very 
important  position.  The  productive  mines  are  situated  in  the 
foothills  of  Pike's  Peak,  about  ten  miles  west  from  the  peak 
itself.  The  summit  is  clearly  visible  from  many  of  them,  as 
are  also  the  peaks  of  the  Sangre  de  Cristo  range,  many  miles  to 
the  south.  The  town  of  Cripple  Creek  lies  in  the  valley  of  the 
small  strearri  of  the  same  name,  which  is  a  branch  of  Oil 
Creek,  itself  a  tributary  of  the  Arkansas  River.  The  valley  is 
an  open  and  moderately  broad  upland,  but  the  approaching 
depressions  are  narrow  defiles,  that  have  presented  great  diffi- 
culties to  railways.  The  general  country  rock  of  the  region  is 
the  red  granite  of  Pike's  Peak.  This  contains  masses  of  still 
older  mica  schists,  presumably  caught  up  in  its  intrusion.  The 

^  R.  N.  Clark,  "  Humboldt- Pocahontas  Vein,"  Trans.  Amer.  Inst.  Mm. 
Eng.,  VII.,  21,  "Silver  Cliff,  Colorado,"  Eng.  and  Min.  Jour.,  Novem- 
ber 3,  1878,  p.  314.  W.  Cross,  "Geology  of  the  Rosita  Hills,"  Proc.  Colo. 
Sei.  Soc,  1890,  p.  269.  Rec.  Seventeenth  Ann.  Rep.  U.  S.  Geol.  Survey, 
Part  II.,  269.  Rec.  S.  F.  Emmons,  "The  Genesis  of  Certain  Ore  Depos- 
its," Trans.  Amer.  Inst.  Min.  Eng.,  XV.,  146.  Tenth  Census,  Vol.  XIII., 
p.  80.  "The  Mines  of  Custer  County,  Colo. ,"  Seventeenth  Ann.  Rep.  U. 
S.  Geol.  Survey,  Part  II.,  411.  Rec.  L.  C.  Graybill,  "On  the  Peculiar 
Features  of  the  Bassick  Mine,"  Trans.  Amer.  Inst.  Min.  Eng.,  XI.,  p.  110; 
Eng.  and  Min.  Jour. ,  October  28,  1882,  p.  226.  Rec.  O.  Loew  and  A.  R. 
Conkling,  "Rosita  and  Vicinity,"  Wheeler's  Survey,  1876,  p.  48.  See  also 
Stevenson  in  the  Report  for  1873. 


302  KEMP'S  ORE  DEPOSITS. 

schists  are  pre-CambriaD,  as  are  the  granites  and  certain  dia- 
base dikes  that  occur  in  the  streets  of  Cripple  Creek  and  on 
Mineral  Hill,  but  that  are  of  no  importance  in  connection  with 
the  ores.  At  the  close  of  the  Eocene  or  in  the  Miocene  times  a 
small  volcanic  center  broke  out  in  the  granite  hills  now  lying 
east  of  the  town,  and  perhaps  elsewhere.  It  was  marked  at 
first  by  explosive  activity  that  besprinkled  the  neighboring 
region  with  a  breccia  made  up  of  fragments  of  granite  and 
andesite.  Later  came  eruptions  of  phonolite  of  one  or  two 
varieties  that  form  many  dikes  associated  with  the  ore  bodies. 
Some  minor  outcrops  of  nepheline-syenite  and  syenite-porphyry 
are  possibly  deep-seated  and  coarsely  crystalline  representatives 
of  the  phonolite  magma.  Explosive  eruptions  of  this  phase  seem 
also  to  have  contributed  some  phonolite  to  later  breccias.  Last 
of  all,  dikes  of  several  kinds  of  basalt,  including  nepheline 
basalt,  feldspar  basalt,  and  limburgite,  closed  the  eruptive  phe- 
nomena. The  breccias,  after  their  formation,  became  in  many 
cases  silicified,  so  as  to  produce  a  very  firm  rock,  and  as  a  rule 
are  so  altered  that  their  original  rock  is  to  be  recognized  more 
by  its  physical  texture  than  its  mineralogy.  In  areal  distribu- 
tion the  breccias  are  the  most  prominent  rocks  near  the  mines; 
next  follows  the  granite,  while  through  both  are  intruded  the 
dikes  of  phonolite  and  basalt. 

The  ores  are  almost  entirely  productive  of  gold,  for  although 
some  little  silver  often  occurs  with  it,  and  although  lead,  zinc 
and  copper  minerals  are  met  in  one  or  two  mines,  the  former  is  of 
slight  economic  account  and  the  latter  are  rareties.  Iron  pyrites 
is  very  widespread,  but  it  is  not  a  great  carrier  of  gold.  The 
real  source  is  the  telluride  of  gold,  calaverite,  froiu  which 
more  or  less  of  the  native  metal  has  been  derived  in  the  uppor 
parts  of  the  veins  by  oxidation.  The  gangue  minerals  are 
quartz,  fiuorite  and  decomposed  country  rock.  When  the  lat- 
ter is  granite,  it  has  lost  its  mica  and  often  its  quartz,  leaving 
a  cellular  rock  more  or  less  impregnated  with  fresh  or  decom- 
posed telluride.  The  wash  of  these  veins  has  yielded  some 
placer  diggings,  especially  on  Mineral  Hill. 

The  ore  deposits  are  true  veins  that  have  been  formed  along 
lines  of  displacement  whose  amount  is,  as  a  rule,  slight.  The 
fissures  themselves  are  often  insignificant  in  appearance,  but 
the  impreguations  of  the  wall  rock  with  ore  to  a  width  of  from 


Fig.  109. — View  of  Cripple  Creek,  Colorado,  from  Mineral  Hill;  Gold  Hill 
in  the  background.     From  a  photograph  by  J.  F.  Kemp,  July,  1895. 


Fig.  no.— View  of  Battle  Mountain,  Victor,  Colorado.     From  a  window 

in  Victor.     The  Portland  group  of  mines  is  on  the  left  in  the 

background.     The  Independence  mine  is  on  the 

extreme  right.     From  a  photograph  by 

J.  F.  Kemp,  July,  1895. 


mr^^^^i^ 


304 


KEMP'S  ORE  DEPOSITS. 


one  to  several  feet  afford  very  rich  and  valuable  ore  bod- 
ies. The  fissures  frequently  foUov^r  the  courses  of  dikes,  but  are 
clearly  later  than  the  latter  because  they  cross  them,  leave 
them,  return  to  them,  and  behave  in  a  more  or  less  independent 
way.  Yet  the  presence  of  dikes  is  in  a  measure  a  favorable 
thing,  because  the  dike  itself  has  filled  a  fissure,  and  because 
it,  being  an  offshoot  from  a  larger  body  of  heated  rock,  and 
with  lines  of  weakness  along  the  contacts  with  its  walls,  doubt- 
less has  often  exercised  a  directing  influence  on  solutions.     The 


[Fig.  113. — Stereogram  of  the  Annie  Lee  ore-short,  Victor,  Colo.     After  R.  A. 
F.  Penrose,  XVI.  Ann.  Rep.  U.  S.  Oeol.  Survey,  Part  II,  p.  206. 

accompanying  map,  from  the  timely  and  valuable  report  of 
Cross  and  Penrose,  which,  with  the  Pike's  Peak  Atlas  Sheet  of 
the  U.  S.  Geological  Survey,  should  be  consulted  by  all  who 
are  especially  interested  in  the  region,  will  give  the  main  fea- 
tures of  the  geology.  The  veins  are  not  large,  but  they  have 
yielded  in  the  aggregate  great  amounts  of  high  grade  ore.  As 
elsewhere  the  ores  follow  shoots  in  the  veins,  and  the  shoots 
approximate  the  vertical.  Small  cross  fractures  have  often 
exercised  an  influence  upon  them.     The  veins  themselves  are 


SILVER  AND  GOLD.  305 

also  often  in  a  series  of  small  parallel  fissures,  rather  than  in 
a  single  one,  and  impregnate  the  intervening  walls.  Ore  has 
been  found  in  blind  veins,  outside  the  main  lines  of  deposition, 
so  that  frequent  cross-cuts  are  desirable  to  make  sure  of  the 
country.  The  most  productive  section  is  on  Battle  Mountain, 
just  above  Victor.  The  Portland  group  and  the  famous  Inde- 
pendence, of  which  a  cut  is  here  reproduced  from  Penrose's 
report,  are  in  this  hill.  Fig.  112  illustrates  the  Annie  Lee 
ore- body,  a  very  curious  one  that  forms  a  chimney  in  a  basaltic 
dike.  Bull  Mountain,  with  its  spur.  Bull  Cliff,  contains  a 
considerable  number  around  the  town  of  Altman.  The  fissure 
on  which  the  Buena  Vista,  Lee  and  Victor  mines  are  located 
is  one  of  the  most  extended  in  the  district.  Raven  Hill,  Gold 
Hill,  Globe  Hill  and  various  minor  spurs  have  also  yielded 
important  bodies  of  ore.^ 

It  has  been  customary  to  send  the  ores  up  to  $20  to  the  ton  to 
the  stamp  mills,  for  which  treatment,  however,  they  are  not 
well  adapted,  as  the  losses  are  heavy.  Ores  from  $20 — $40  go 
to  the  cyanide  mills,  and  above  $40  to  the  smelters. 

2.09.22.  Gilpin  County  has  already  been  mentioned  under 
"Copper"  (2.04.08).  The  general  geology  of  the  veins  is  much 
like  that  of  Clear  Creek,  although  the  ores  are  quite  different. 

^  W.  P.  Blake,  "The  Gold  of  Cripple  Creek,"  Eng.  and  Min.  Jour.,  Jan- 
uary 13,  1894.  Whitman  Cross,  Pike's  Peak  Atlas  Folio  of  the  U.  S.  Geol. 
Survey ;  to  be  obtained  by  sending  25  cents  to  the  Director  of  the  Survey, 
Washington,  D.  C.  Rec.  Whitman  Cross  and  R.  A.  F.  Penrose,  Jr., 
"Geology  and  Mining  Industries  of  the  Cripple  Creek  District.  Colorado," 
Sixteenth  Ann.  Rep.  of  the  Director  of  the  U.  S.  Geol.  Survey,  1894-95. 
Rec.  W.  F.  Hillebrand,  "Chemical  Composition  of  Calaverite  from  Crip- 
ple Creek,"  in  Cross  and  Penrose's  Report,  p.  133.  W.  H.  Hobbs,  "Gold- 
schmidtite,  a  New  Mineral,"  Amer.  Jour.  Sci.,  May,  1899,  357.  F.  G. 
Knight,  "On  the  Composition  of  the  Cripple  Creek  Telluride,"  Proc.  Colo. 
Sci.  Joe,  October  1,  1894.  H.  L.  McCarn,  "Notes  on  the  Geology  of  the 
Gold  Field  of  Cripple  Creek,  Colo.,"  Science,  January  19,  1894,  p.  31.  R. 
Pearce,  "The  Mode  of  Occurrence  of  Gold  in  the  Cripple  Creek  District," 
Proc.  Colo.  Sci.  Soc,  January  8,  1894;  Eng.  and  Min.  Jour.,  March  24, 
1894.  "Further  Notes  on  Cripple  Creek  Ores,"  Proc.  Colo.  Sci.  Soc,  April 
Ti,  1894.  S.  L.  Penfield,  "On  Calaverite  Crystals  from  Cripple  Creek," 
Cross  and  Penrose's  Report,  p.  135.  E.  Skewes  and  H.  J.  Eder,  "The  Vic- 
tor Mine,  Cripple  Creek,  Colo,"  Eng.  and  Min.  Jour.,  August  19,  1893,  p. 
198.  E.  Skewes,  "The  Ore  Shoots  of  Cripple  Creek,"  Trans.  Amer.  Inst. 
Min.  Eng.,  September,  1896.  G.  H.  Stone,  "The  Granitic  Breccias  of 
the  Cripple  Creek  Region,"  Amer.  Jour.  Sci.,  January,  1898,  21. 


306  KEMP'S  ORE  DEPOSITS. 

R.  Pearce  has  shown  the  existence  of  bismuth  in  the  ore,  anct 
gives  reasons  for  believing  that  the  gold  is  in  combination  with 
it.  Clear  Creek  County  contains  veins  on  a  great  series  of 
jointing  planes  in  gneiss  (granite),  and  in  large  part  replace- 
ments of  the  wall.  Others  are  replacements  of  porphyry  dikes 
or  of  pegmatite  segregations.  The  ores  are  chiefly  galena, 
tetrahedrite,  zincblende,  and  pyrite,.  and  the  gangue  is  the  wall 
rock.  The  curious  decrease  of  value  in  depth  of  a  series  of 
parallel  veins  in  Mount  Marshall  was  earlier  referred  to 
(1.05.05).  Georgetown  is  the  principal  town  and  mining  center. 
Others  of  importance  are  Idaho  Springs  and  Silver  Plume. ^ 

2.09.23.  Boulder  County  contains  veins  along  joints  or 
faulting  planes  in  gneiss,  or  granite,  or  associated  with  por- 
phyry dikes,  or  pegmatite  segregations,  and  carrying  tellurides 
of  the  precious  metals  more  or  less  as  impregnations  of  the 
country  rock.  The  prevalent  country  rock  is  called  by  Emmons 
a  granite-gneiss.  Van  Diest  distinguishes  four  successive  ter- 
ranes  of  massive  and  schistose  rocks  along  three  principal  axes 
and  two  side  ones,  and  states  that  the  mines  are  on  the  sides  of 
the  folds.  The  country  is  very  generally  pierced  by  porphyry 
dikes,  with  which  the  ore  bodies  are  often  associated.  A  large 
number  of  species  of  telluride  minerals  have  been  determined 
from  the  region,  especially  by  the  late  Dr.  Genth,  of  Philadel- 
phia. The  mines  afford  very  rich  ores,  somewhat  irregularly 
distributed.^ 

'  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  70.  Rec.  F.  M.  Endlich, 
Hayden's  Survey,  1873,  p.  293;  1876,  p.  117.  P.  Fraser,  Hayden's  Survey, 
1869,  p.  lot  J.  D.  Hague,  Fortieth  Parallel  Survey,  Vol.  III.,  p.  589. 
Rec.  R.  Pearce,  Proc.  Colo.  Sci.  Soc,  Vol.  III.,  pp.  71,  210.  "The  Asso- 
ciation of  Gold  with  Other  Metals  in  the  West,"  Trans.  Amer.  Inst.  Min. 
Eng.,  XVIII.,  447,  1890.  Forbes  Rickard,  "Notes  on  the  Vein  Formation 
and  Mining  of  Gilpin  County,  Colo.,"  Trans.  Amer.  Inst.  Min.  Eng.,  Feb- 
ruary, 1898.  J.  J.  Stevenson,  Wheeler's  Survey,  Vol.  III.,  p.  351.  F.  L. 
Vinton,  "The  Georgetown  (Colo.)  Mines,"  Eng.  and  Min.  Jour.,  Septem- 
ber 13,  1879,  p.  184. 

'^  Bergrath  Burkart,  "Ueber  das  Vorkommon  Verschiedener  Tellur- 
Minerale  in  den  Vereinigten  Staaten  von  Nordamerika, "  Neues  Jahrbuch^ 
1873,  476;  April,  492,  1874,  30.  Whitman  Cross,  "A  List  of  Specially 
Noteworthy  Minerals  of  Colorado,"  Proc.  Colo.  Sci.  Soc,  I.,  134,  1884;  cites 
Tellurium,  Melonite,  Altaite,  Hessite,  Coloradoite,  Sylvanite,  Tellurite. 
A.  Filers,  "A  New  Occurrence  of  the  Telluride  of  Gold  and  Silver,"  Trans. 
Amer.  'Inst  Min.   Eng.,  I.,   316,  1872.     Red  Cloud  Mine.     S.  F.  Emmons,. 


SILVER  AND  OOLD.  307 

2.09.25.     The  resources  of  the  remaining  counties  of  Colo- 
rado are  chiefly  in  coal. 

"Sketch of  Boulder  County,"  Tenth  Census,  Vol.  XIII.,  p.  64, 1885.  F.  M 
Endlich,  "  Tellurium  Ores  of  Colorado,"  Eng.  and  Min.  Jour.,  XVIII,  183, 
1874.  F.  M.  Endlich,  "  Minerals  of  Colorado  Territory, "  jEZat/den's  ^'ttr?;ei|/, 
1873,  353.  J.  B.  Farish,  "  Interesting  Vein  Phenomena  in  Boulder  County, 
Colo."  (Golden  Age  Mine),  Trans.  Amer.  Inst.  Min.  Eng.,  XIX.,  541,  1890, 
"A  Boulder  County  Mine "  {The  Golden  Age  and  Sentinel),  Proc.  Colo. 
Sci.  Soc.,  III.,  316,  1890  (same  as  above).  F.  A.  Genth,  " On  Tellurides 
from  Red  Cloud  and  Uncle  Sam  Lodes,"  Proc.  Arner.  Phil.  Soc,  XIV., 
225,  1874.  "Tellurides  from  Keystone,  Mountain  Lion,  and  John  Jay 
Mines,"  Idem,  XVIL,  115,  1877.  J.  K.  Hallowell,  "Boulder  County  as 
It  Is,"  Denver,  1882.  Worthless.  N.  P.  Hill,  "Announces  Tellurides  at 
Red  Cloud  Mine,"  Amer.  Jour.  Scl,  V.,  387,  May,  1873.  W.  F.  Hillebrand, 
"Melonite  Forlorn  Hope  Mine,  Boulder  County,"  Proc.  Colo.  Sci.  Soc,  I., 
123, 1884.  E.  P.  Jennings,  "Analyses  of  Some  Tellurium  Minerals  "  (Native 
Tellurium  from  John  Jay  Mine;  Sylvanite,  Smuggler  Mine),  Trans.  Amer. 
Inst.  Min.  Eng.,  YI.,  506,  1877.  A.  Lakes,  "  On  Boulder  County"  Geology  of 
Colorado  Ore  Deposits,  c.  1888.  A.  R.  Marvin,  "  Metamorphic  Crystalline 
Rocks  of  the  Front  Range, "  Hayden's  Survey,  1873.  ' '  On  Boulder  County, " 
pp.  144,  147-152,  685.  Map.  C.  L.  Palmer,  "Eruptive  Rocks  of  Boulder 
County,  Colorado,"  Proc  Colo.  Sci.  Soc,  III.,  230,  1889.  C.  L.  Palmer 
and  Henry  Fulton,  "The  Quartz  Porphyry  of  Flagstaff  Hill,  Boulder, 
Colorado,"  Idem,  351,  1890.  R.  Pearce,  "Remarks  on  Gold  Ores  of 
Rocky  Mountains,"  R.  Pearce,  In  Discussion  of  Paper  by  P.  H.  Van 
Diest,  Proc  Colo.  Sci.  Soc,  IV.,  349,  1893.  B.  Silliman,  "Mineral- 
ogical  Notes;  Tellurium  Ores  in  Colorado,"  ^mer.  Jour.  Sci.,  July,  1874, 
25-33.  Reprinted  in  Hayden's  Report,  1873,  686.  J.  Alden  Smith, 
quoted  by  P.  H.  Van  Diest  as  mentioning  Boulder  County  Mines  in  his 
Biennial  Report  for  1880.  P.  H.  Van  Diest,  "  Notes  on  Boulder  County 
Veins,"  Proc.  Colo.  Sci.  Soc,  II.,  50,  1886.  "The  Mineral  Resources  of 
Boulder  County,  Colorado, "  Biennial  Rep.  State  School  of  Mines,  1886,  25. 
P.  H.  Van  Diest,  ' '  Evidence  Bearing  on  the  Formation  of  Ore  Deposits 
by  Lateral  Secretion ;  The  John  Jay  Mine  at  Boulder  County,  Colorado," 
Proc  Colo.  Sei.  Soc,  IV.,  340,  18. 


CHAPTER  X. 

SILVER    AND    GOLD,    CONTINUED.— ROCKY  MOUNTAIN  REGION, 
WYOMING,   THE  BLACK  HILLS,   MONTANA,   AND  IDAHO. 

WYOMING. 

2.10.01.  Geology, — The  southeastern  part  of  Wyoming  is 
in  the  region  of  the  Great  Plains,  the  southwestern  in  the  Colo- 
rado Plateau.  The  Rocky  Mountains  shade  out  more  or  less 
on  leaving  Colorado,  but  are  again  strongly  developed  in  north- 
ern Wyoming.  The  northwestern  portion  contains  the  great 
volcanic  district  of  the  National  Park,  and  the  northeastern,  a 
part  of  the  Black  Hills.  The  Cretaceous  and  Tertiary  strata 
chiefly  form  the  plains  and  plateaus.  Granite  and  gneiss  con- 
stitute the  central  portion  of  some  of  the  greater  ranges.  Pale- 
ozoic rocks  are  very  subordinate.  The  resources  in  precious 
metals  so  far  as  yet  developed  are  small,  consisting  chiefly  of 
gold  in  quartz  veins  in  the  gneisses,  schists  and  granites  of 
Sweetwater  County.  The  great  mineral  wealth  of  the  State  is 
in  coal.  The  iron  mines  have  already  been  mentioned  (2.03.09), 
and  the  copper  (2.04.27).^ 

^  H.  M.  Chance,  "  Resources  of  the  Black  Hills  and  Big  Horn  Country, 
Wyoming,"  Trans.  Amer.  Inst.  Min.  Eng.,  XIX.,  p.  49.  T.  B.  Comstock, 
"On  the  Geology  of  Western  Wyoming,"  Amer.  Jour.  Sci.,  iii.,  VI.,  426. 
S.  F.  Emmons,  Tenth  Cenms,  Vol.  XIII.,  p.  86.  F.  M.  Endlich,  "The 
Sweetwater  District,"  Hayden's  Survey,  1877,  p.  5;  "Wind  River  Range 
Gold  Washings,"  p.  64.  A.  Hague,  "Geological  History  of  the  Yellow- 
stone National  Park,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  783,  and 
Yellowstone  Park  Folio,  U.  S.  Geol.  Surv.  See  also  F.  V.  Hayden,  Amer. 
Jour.  Sci.,  iii.,  HI.,  105,  151.  F.  V.  Hayden.  Rep.  /or  1870-72.  p.  13; 
also  Amer.  Jour.  Sci.,  ii.,  XXXI.,  229.  A.  C.  Peale,  "Report  on  the 
Geology  of  the  Green  River  District."  Hayden's  Survey,  1877,  p.  511. 
Raymond's  Statistics  West  of  the  Rocky  Mountains.  W.  C.  Knight,  Bull. 
U,  Wyo.  Exp't  Station,  October,  1893. 


SILVER  AND  GOLD,   CONTINUED. 


309 


SOUTH   DAKOTA.— THE   BLACK   HILLS. 

2.10.02.  Geology.— The  Black  Hills  lie  mostly  m  South  Da- 
kota. They  consist  of  a  somewhat  elliptical  core  of  granite 
and  metamorphic  rocks,  with  a  north  and  south  axis,  and  on 
these  are  laid  down  successive  strata  of  Cambrian,  Carbonifer- 
ous, Jura- Trias,  and  Cretaceous  rocks.  There  are  some  igne- 
ous intrusions.  The  principal  product  of  the  Black  Hills  is 
gold.  The  lead-silver  deposits  have  already  been  described 
(2.08.18),  and  the  tin,  etc.,  will  be  mentioned  later.^ 


Fig.  113. — Geological  section  of  the  Black  Hills.     After  Henry  Newton  Report 
on  the  Black  Hills,  p.  206. 

1.  Schists.    2.  Granite.    3.  Potsdam  sandstone.    4.  Carboniferous.    5,  6,  Jura-Trias. 

7.  Cretaceous. 

2.10.03.  The  gold  occurs  in  stream  placers  of  Quarternary 
and  recent  age,  and  of  no  great  importance;  in  supposed,  old 
beach  or  channel  placers  in  the  Cambrian  (so-called  Potsdam), 
conglomerates,  the  **cement"  deposits;  in  impregnations  of  the 

^  F.  R.  Carpenter,  "Ore  Deposits  in  the  Black  Hills,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XVII.,  570.  Prelim.  Rep.  on  the  Geol.  of  the  Black  Hills, 
Rapid  City,  So.  Dakota,  1888.  W.  O.  Crosby,  "Geology  of  the  Black 
Hills,"  Bosf.  Soc.  Nat.  Hist.,  XXIII.,  p.  89.  P.  Frazer,  "Notes  on  the 
Northern  Black  Hills  of  South  Dakota,"  Trans.  Amer.  Inst.  Min.  Eng., 
XXVII.,  204,  1897.  John  D.  Irving,  "A  Contribution  to  the  Geology  and 
Ore  Deposits  of  the  Northern  Black  Hills,  South  Dakota,"  Annals  N.  Y. 
Acad.  Sciences,  XII.,  Part  II.,  1899.  Rec.  Newton  and  Jenney,  Report  on 
the  Black  Hills,  Washington,  1880.  F.  C.  Smith,  "The  Occurrence  and 
Behavior  of  Tellurium  in  Gold  Ores,  more  particularly  with  Reference  to 
the  Potsdam  Ores  of  the  Black  Hills,"  Trans.  Amer.  Inst.  Min.  Eng., 
XXVI.,  485,  1103,  1896.  "  The  Potsdam  Gold  Ores  of  the  Black  Hills  of 
South  Dakota,"  Idem,  XXVII.,  404,  428,  1897.  Rec.  C.  R.  Van  Hise, 
"The  Pre-Cambrian  Rocks  of  the  Black  Hills,"  Bull.  Geol.  Soc.  Amer.,  I., 
203-244.  N.  H.  Winchell,  "Report  on  the  Black  Hills,"  i^ep.  Chief,  of 
U.  S.  Engineers,  1874,  Part  II.,  p.  630.  The  U.  S.  Geological  Survey  is 
preparing  a  report  on  the  Black  Hills,  S.  F.  Emmons  and  T.  A.  Jaggar 
being  in  charge  of  the  work. 


310 


KEMP'S  ORE  DEPOSITS. 


Cambrian  lime-shales,  with  siliceous  gold  ores  in  the  neigh- 
borhood of  intruded  dikes  and  sheets  of  phonolite;  in  crevices  in 
the  heavy  Carboniferous  limestone,  now  filled  with  siliceoup 
gold  ores;  and  in  broad  zones  or  fahlbands  of  Algonkian  slaty 
and  mica  schists,  carrying  auriferous  pyrites.     The  above  are 


CAMBMAN  '  SHALOS 


ALGONKIAN  SUTES.   aUAimiTCS  J  tVU 


Fig.  114. — Geological  section  of  the  strata  in  the  Northern  Black  Hills,  S.  D, 

After  John  D.  Irving,  Annals  of  the  New  York  Academy  of 

Sciences,  XII,  Part  II,  1899. 

found  in  the  northern  Hills.  In  the  central  portion  pegmatites 
have  recently  proved  gold-bearing.  The  Quarternary  and  recent 
gravels  were  effective  in  attracting  prospectors  in  the  early 
days  of  settlement.  They  are  scarcely  worked  to-day.  The 
ancient  beach  gravels  are  still  followed  beneath  the  caps  of  por- 
phyry in  some  small  mines  in  Deadwood  Gulch.     As  described 


SILVER  AND   GOLD,   CONTINUED. 


:ni 


l3y  W.  B.  Devereux  in  1882,  the  gravels  were  regarded  as  hav- 
ing derived  their  gold  by  the  beating  of  the  waves  of  the  Cam- 
brian Ocean  against  the  auriferous  schists  described  below,  but 
later  work  has  made  it  probable  that  they  are  impregnations 
like  the  Potsdam  siliceous  ores.  The  pay  gravel  now  runs 
as  a  shoot  under  the  later  lava  sheets.  The  impregnations  of 
the  Cambrian,  locally  called  Potsdam,  lime-shales  with  tellu- 


Cambrian5hale 
and  Sandrock. 
(Very  Calcareous) 

Cambrian  Qnartzite 

and  Conglomerate 

("Cement") 


Algonkian 


Plan  of  Ore  Chute. 

The  ore  is  broken  awat 

TO  show  the  verticals. 

Fig.  115. — Plan  and  cross-section  of  a  Cambrian,  siliceous  gold-ore  deposit  in 

the  Black  Hills,  8.  D.     After  John  D.  Irving,  Annals  N.  Y. 

Atademy  of  Sciences,  XTI,  Part  11. ,  1899. 

rides  and  pyrites,  constitute  a  form  of  ore  body  that  has  been  of 
rather  recent  development,  but  that  is  now  the  leading  producer. 
The  mines,  as  indeed  nearly  all  the  gold  developments,  are  in 
the  northern  Hills,  and  are  especially  abundant  around  Terry 
Peak.  The  Cambrian  lies  flat,  and  is  penetrated  very  abun- 
dantly by  dikes  and  sheets  of  trachyte  and  phonolite.     The  ig- 


312  KEMP'S  ORE  DEPOSITS. 

neous  rocks  have  themselves  sometimes  been  impregoated,  when 
they  lie  near  an  ore  body.  Associated  with  the  ore  shoots  and 
usually  bisecting  that  portion  of  the  floor  that  lies  beneath  them 
are  found  cracks,  called  "verticals,"  that  run  down  to  unknown 
depths,  but  that  are  not  accompanied  by  any  notable,  if,  in- 
deed, by  any  appreciable  faulting.  The  verticals  have  di- 
rected, or  ha\e  served  to  introduce  the  solutions,  which  have 
then  spread  laterally  into  beds  of  lime-shales  and  have  replaced 


,4ttHt:nn:n+porphyryntttutuu:ru:i:-K 


■+  +  ++-)-  +  +  +4-+-|. 


Fig.  116. — Plan  and  section.  Mail  and  Express  Mine,  to  illustrate  the  siliceous 

gold  ores  of  the  Black  Hills,  8.  D.     After  John  D.  Irmng,  Annals 

N.  T.  Academy  of  Sciences,  XIL,  Part  IL,  1899. 

the  calcareous  portion  of  them  with  ore  and  silica.  Those  beds 
of  lime-shales  have  proved  most  favorable  which  rest  upon  a 
floor  of  hard  quartzite,  and  this  association  is  so  constant  that 
the  miners,  in  regions  of  phonolite  sheets,  sink  to  the  quartzite, 
and  then  explore  for  ore.  The  ore  runs  in  long  shoots  on  the 
strike  of  the  verticals. 

The  ores  contain  as  gangue  quartz,  fluorite  and  the  unre- 
placed  residue  of  the  lime -shales.     The  metallic  minerals  are 


Fig.  117.— Green  Mountain,  Black  Hills,  S.D  ;  a  laccolite  of  phonolite,  with 

the  mines  of  siliceous  ore  on  the  so-called  ' '  upper  contact "  around 

its  foot     Photographed  by  John  D.  Irving,  1898. 


Fig.  118. — Vieiv  of  tiie  Union  Mine,  in  siliceous  ore,  near  Terry,  in  the 
Black  Hills,  S.  D.     Photographed  by  John  D.  Irving,    1898. 


Siliceous  Gold  Ore 
IN  Limestone. 


Enlarged  Boulder 
showing  Siliciflcation 
\\';ill-  ]   of  Brecciated  Limestone  and 
line  of  demarcation  between 
the  Oi-e  and  Wall-rock 


Type  of  Ragged  Top  Vertical 
IN  Carboniferous  Limestone 
on  Dacy  flat 
Lawrence  Co, 
South  Dakota. 


Fig.  120. — Pevfipect ire  cross-section  of  siliceous  gold  ore  in  Carboniferous 

limestone,  Dacy  Flat,  Black  Hills.    After  John  D.  Irving,  Annals 

N.  Y.  Academy  of  Sciences,  XII.,  Part  11,  1899. 


Fig.  121. — View  of  the  Golden  Star  open  cut.  Lead  City,  S.  D.     From 
a  photograph  by  J.  F.  Kemp,  1896. 


SILVER  AND  GOLD,   CONTINUED.  313 

pyrite  and  a  supposed  telluride  of  gold,  whose  presence  is  indi- 
cated by  analysis,  but  which  has  not  been  actually  seen.  Tho- 
rium has  also  been  detected  by  F.  C.  Smith.  There  are  two 
varieties,  red,  or  oxidized,  ores,  and  blue,  or  unoxidized.  They 
are  collectively  known  as  siliceous  or  Potsdam  ores.  The 
presence  of  tellurium,  of  fluorite,  and  of  phonolite  is  highly 
suggestive  of  Cripple  Creek,  Colo.,  and  of  several  newer  dis- 
tricts in  Montana.  At  times  the  vertical  may  lie  alongside  of 
an  intruded  dike  as  shown  in  Fig.  119,  and  then  the  ore  fol- 
lows the  dike  and  may  impregnate  it  more  or  less. 

The  intruded  igneous  rocks  have  seldom  been  able  to  pierce 
the  heavy  cap  of  Carboniferous  limestone,  but  the  laccolites 


YlOt.  119.— Cross-section  of  a  siliceous  gold-ore  body  lying  next  to  a  prophyry 

dike,  Black  Hills,  8.  D.     After  John  D.  Irving,  Annals  N.  T. 

Academy  of  Sbiences,  XII.,  Part  II.,  1899. 

have  served  to  dome  it  up,  and  to  fissure  it  more  or  less.  In 
the  vicinity  of  the  Ragged  Top  laccolite,  on  Dacy  Flat,  these 
fissures  or  crevices  have  been  the  seat  of  the  deposition  of  rich, 
siliceous  ores.  The  ores  have  replaced  and  cemented  into  a 
hard  aggregate,  the  brecciated  limestone  that  filled  the  fissure 
before  their  introduction.     (See  Fig.  120.) 

The  older,  and  formerly  the  chief  source  of  gold  in  the  Black 
Hills,  is  in  the  great  zone  or  fahlband  of  schists  near  Lead  City, 
which  carries  little  lenses  and  vein  lets  of  quartz,  with  aurifer- 
ous pyrites.  The  pay  is  thought  to  lie  in  the  schists.  The  ores 
are  free-milling,  and  are  controlled  by  the  Homestake  Com- 
pany.    They  are  situated  in  and  near  Lead  City,  in  hills  which 


314  KEMP'S  ORE  DEPOSITS. 

form  steep  divides  between  the  narrow  gulches.  The  schists 
strike  about  N.  20  W.,  and  dip  60  E.,  and  in  the  Golden  Star 
are  stoped  out  in  a  cross-section  over  450  feet.  Porphyry  dikes 
cut  the  schists,  and  have  spread  laterally,  so  as  in  their  present 
eroded  condition  to  appear  like  surface  caps  of  lava.  They  may 
have  exercised  an  important  influence  in  the  enrichment  of  the 
schists,  but  it  seems  certain  that  gold  was  present  in  them  in 
the  Cambrian  times,  because  the  Cambrian  sediments  when 
carefully  panned  almost  always  afford  some  trace  of  the  yellow 
metal.  The  special  local  enrichment  of  the  schists  may  have 
been  influenced  by  the  porphyry.  The  ores  are  low  grade,  run- 
ning $3— $4  or  less.  The  Old  Abe,  Golden  Star,  Dead  wood- 
Terra  and  Father  de  Smet  are  the  chief  locations.^ 

In  addition  to  the  types  of  ore  body  described  above,  there  are 
found  throughout  the  schists  of  the  Hills  occasional  quartz 
veins,  of  the  old  so-called  "segregated"  variety,  that  have 
yielded  a  little  gold.  Recently  pegmatites  near  Harney  Peak 
have  proved  productive,  affording  ores  similar  in  their  geology 
to  those  described  by  Hussak  from  Ouro  Preto,  Brazil,^  and 
to  some  in  the  Transvaal. 

MONTANA. 

2.10.04.  Geology. — The  eastern  part  of  the  State  belongs  to 
the  region  of  the  Great  Plains,  which  is,  however,  in  portions 
greatly  scarred  by  erosion,  forming  the  so-called  Bad  Lands. 
The  approaches  to  the  Rocky  Mountains  are  not  abrupt  and 
sudden  as  in  Colorado,  but  are  marked  by  numbers  of  outlying 
ranges  of  both  eruptive  and  sedimentary  rocks.  The  chain  of 
the  Rockies  takes  a  northwesterly  trend  in  Wyoming,  and  so 
continues  across  Montana.  It  is  rather  the  prolongation  of  the 
Wasatch  than  of  the  Colorado  Mountains,  whose  strike  is  for 
the  Black  Hills.     The  character  of  the  ranges  is  also  very  dif- 

*  A.  J.  Bowie,  "Notes  on  Gold  Mill  Construction,"  Trans.  Amer.  Inst. 
Min.  Eng.,  X.,  87,  1881.  W.  B.'  Devereux,  "The  Occurrence  of  Gold  in 
the  Potsdam  Formation,"  Idem,  X.,  465:  Eng.  and  Min.  Jour.,  December 
23,  1882,  p.  334.  H.  O.  Hoffman,  "Gold  Mining  in  the  Black  Hills," 
Trans.  Amer.  Inst.  Min.  Eng. ,  XVII. ,  498 ;  also  in  preliminary  report  cited 
under  Carpenter,  under  Geology.     See,  in  addition,  references  on  pa^e  309. 

*  E.  Hussak.  "Der  goldfiihrende,  kiesige  Quarzlagergang  von  Passagem 
in  Minas  Geraes,  Brasilien,"  Zeits.  furprakt.  Geologie,  October,  1898,  345. 


8ILVEB  AND  GOLD,   CONTINUED.  315 

ferent.  They  are  less  elevated,  and  have  broad  and  well- 
watered  valleys  between,  that  admit  of  considerable  agricul- 
ture. Geologically  the  country  is  in  marked  contrast  with  Col- 
orado. While  in  the  latter  the  lower  Paleozoic  is  feebly  devel- 
oped, in  Montana  it  is  important.  Special  interest  attaches  to 
the  Lower  Cambrian  or  perhaps  pre- Cambrian  quartzites  and 
associated  sediments  that  are  present  in  great  thickness  in  the 
northwestern  part  of  the  State,  and  along  the  Idaho  line.  Fos- 
sils have  recently  been  reported  by  C.  D.  Walcott  from  a  very 
low  horizon.  On  the  east  of  the  Continental  Divide  the 
gneisses  and  schists  of  the  Archean  are  succeeded  by  metamor- 
phosed sediments  of  the  Algonkian,  involving  7,000  feet  or 
more,  and  known  as  the  Cherry  Creek  formation  of  the  U.  S. 
Geologists.  Unconformablj'  upon  this  lies  the  Belt  formation, 
of  6,000  to  10,000  feet  of  sediments,  which  are  doubtfully  re- 
ferred to  the  Algonkian.  Still  above  come  the  true  Cambrian, 
1,000  to  1,500  feet;  Siluro-Devonian  (of  which  the  latter  alone  is 
identified  by  fossils),  200  to  600  feet;  Carboniferous  limestones, 
800  to  1,000  feet,  followed  by  a  quartzite  and  shale  series  of  200 
to  600  feet;  Jura- Trias  up  to  500  feet;  and  then  some  thou- 
sands of  feet  of  Cretaceous  and  Tertiary.  Great  batholites  of 
granite,  in  part  at  least  post-Carboniferous,  have  been  intruded 
as  set  forth  earlier  under  Butte,  2.04.05.  They  have  basic  phases 
on  the  margins,  and  locally,  within  the  masses,  as  at  Butte. 
The  above  grouping  modifies  somewhat  the  section  given  in 
earlier  editions  of  this  work,  and  has  resulted  from  the  more 
recent  work  of  W.  H.  Weed  and  A.  C.  Peale  of  the  U.  S.  Ge- 
ological Survey,  whose  folios  should  be  consulted  for  local  de- 
tails so  far  as  available.  East  of  the  main  chain  of  the  Rock- 
ies there  are  peculiar  isolated  groups  of,  mountains  of  a  lac- 
colite  character,  such  as  the  High  woods,  the  Judith,  and  the 
Little  Rockies.  They  rise  like  huge  blisters  of  sedimentaries, 
forced  up  by  lenticular  sheets  of  intrusives,  and  pierced  by 
dikes  in  vast  numbers.  They  are  rocks  prevailingly  rich  in 
soda,  and  present  many  rare  and  interesting  types  and  some 
striking  parallels  with  the  Black  Hills. ^ 

^  S.  Calvin,  "Iron  Butte:  Some  Preliminary  Notes,"  Amer.  Geol.,  IV.,  95. 
G.  E.  Culver,  "A  Little  Known  Region  of  Northwestern  Montana,"  Wis. 
Acad,  of  Scl,  December  30,  1891.  W.  M.  Davis,  "The  Relation  of  the  Coal 
of  Montana  to  the  Older  Rocks."  Tenth  Census,  Vol.  XV.,  p.  697.     Rec. 


316  KEMP'S  ORE  DEPOSITS. 

2.10.05.  MontaDa  took  the  lead  of  all  the  States  in  1887  in 
the  production  of  silver,  was  second  in  gold,  and  first  in  the 
total  production  of  the  two.  It  is  now  second  to  Colorado  in 
silver,  and  fourth  on  the  list  in  gold,  but  in  copper  it  is  first. 
In  its  mineral  wealth  it  yields  to  no  other  State  in  the  Union. 
The  mining  districts  are  mostly  in  the  western  central  and 
western  portions.  Developments  have  progressed  so  rapidly 
that  all  the  desirable  data  are  not  available. 

2.10.06.  Madison  County.  The  chief  product  is  gold.  Near 
Virginia  City  the  gold-bearing  quartz  forms  veins  in  schists; 
in  the  northeastern  part  of  the  county  the  veins  occur  in  gran- 

J.  Eccles,  ' '  On  the  Mode  of  Occurrence  of  Some  of  the  Volcanic  Rocks  of 
Montana,"  Quar.  Jour.  Geol.  Sci.,  XXXVII.,  399.     G.  H.  Eldridge,  "Mon 
tana  Coal  Fields,'  Tenth  Census,  Vol.  XV.,  p.  739.     S.  F.  Emmons,  Terith 
Census,  Vol.  XIII. ,  97.     Rec .     Haydens  Survey,  Ann.  Rep. ,  1871-72.     .J. 
F.  Kemp,   "On  Tellurides  in  Montana,"  see  The  Mineral  Industry,  VI., 
312,  1898.     W.  S.  Keyes,  in  Brown's  first  report  on  mineral  resources,  etc., 
last  part,  Amer.  Jour.  Sci.,  II.,  46,  431.     Rec.     W.  Lindgren,  "Eruptive 
Rocks."  Tenth  Census,  Vol.  XV.,  p.  719,  forming  Appendix  B  of  Davis's  first 
paper.     See  also  Proc.  Cal.  Acad.  Sci.,  Second  Series,  Vol.  III.,  p.  39.     J.  S. 
Newberry,  "Notes  on  the  Surface  Geology  of  the  Country  Bordering  on 
the  Northern  Pacific  Railroad,"  Annals  N.  Y.  Acad.  Sci.,  Vol.  III.,  242; 
Amer.  Jour.   Sci.,  iii.,  XXX.,   337.     "The  Gnjat  Falls  Coal  Fields,"  in 
Geol.  Notes,  School  of  Mines  Quarterly,  VIII.,  327.     A.  C.  Peale,  Three 
Forks  Folio,  U.  S.   Geol.    Survey,  1896.     Rec.     F.  Rutley,   "Microscopic 
Character  of  the  Vitreous  Rocks  of  Montana,"  Quar.  Jour.  Geol.  Sci., 
XXX  VII.,  391.     See  Eccles,  above.     CD.  Walcott,  "  Pre-Cambrian  Fos- 
siliferous  Formations,"  Bull.  Geol.  Soc.  Amer.,  X.,  199,  1899.    Rec.    W.  H. 
Weed,  "The  Cinnabar  and  Bozeman  Coal  Fields  of  Montana,"  Idem,  II., 
349-364      Eng.   and  Min.   Jour.,  May  14  and  21,  1892.     "Montana  Coal 
Fields,"  Bull.   Geol.  Soc.  Amer.,  III.,  301-330.     Livingston  Folio,  U.  S. 
Geol.  Survey.     Butte  Special  Folio,  Idem;  Little  Belt  Folio,  Idem;  Bull 
Folio  (in  preparation).     Weed  and  Pirsson,    "Highwood  Mountains  of 
Montana,"  Bull.  Geol.  Soc.  Amer.,  VI.,  389,  1895.     "The  Bearpaw  Moun- 
tains of  Montana,  Amer.  Jour.  Sci.,  May,  1896,  283;  June,  p.  301;  Septem- 
ber, p.  136;  October,   p.  188.     "Geology  of  the  Little  Rocky  Mountains.  ' 
Jour.  Geol,  IV.,  399.      "The  Castle  Mountain  Mining  District,"  Bulletin 
139,  U.  S.  Geol.  Survey,  1896.     -"The  Jadith  Mountains,"  Anii.  Rep.  Dir. 
U.  S.  Geol.  Survey,  XVIII.,  1899,  Part  III.,  437.     All  these  are  Rec.     R.  P. 
Whitfield,  "List  of  Fossils  from  Central  Montana,"  Tenth  Census,  Vol. 
XV.,  p.  712;  Appendix  A  to  Davis's  paper.     J.  E.  Wolff,  "Notes  on  the 
Petrography  of  the  Crazy  Mountains,"  etc..    Northern   Trans.    Sim.->ey. 
"  Geology  of  the  Crazy  Mountains,"  Bull.  Geol.  Soc.  Amer.,  III.,  445.     H. 
Wood,  "Flathead  Coal  Basin,"  Eng.  and  Min.  Jour.,  July  16,  1892,  p.  57. 
H.  R.  Wood,  "Mineral  Zones  in  Montana.."  Idem,  September  24, 1892,  p.  29C. 


SILVER  AND  QOLD,  CONTINUED.  317 

ite ;  at  Rochester  the  gold  is  associated  with  galena ;  at  Sheri- 
dan tetrahedrite  and  chalcopyrite  are  found  in  quartz  veins  and 
are  rich  in  gold  and  silver.^  An  interesting  vein  with  tellur- 
ides  has  been  discovered  at  the  Mayflower  mine  in  the  Tobacco 
Root  Mountains.^  It  is  a  fault  fissure  nearly  parallel  to  the 
bedding  of  upturned  Cambrian  limestones.  The  ore  has  re- 
placed the  limestone  and  is  largely  oxidized.  Placers  were  of 
extreme  importance  in  this  county  in  early  days,  and  are  still 
somewhat  worked.  Alder  Gulch ,  near  Virginia  City,  proved 
extraordinarily  rich. 

2.10.07.  Beaverhead  County.  Near  Bannack  City  quartz 
veins  with  auriferous  pyrite  on  the  contact  between  the  lime 
stone  and  so-called  granite.  At  Glendale,  in  the  northern  part 
of  the  count}',  are  the  Hecla  mines,  referred  to  under  *'Lead- 
silver"  (Example  32).  Auriferous  quartz  veins  are  reported 
farther  north.  ^ 

2.10.08.  Jefferson  County.  There  are  many  varieties  of  ore 
bodies  in  this  county,  but  the  commonest  type  is  similar  to  that 
at  Butte,  i.e.,  veins  in  granite  along  fissures  of  slight  displace- 
ment. The  ore  is  altered  country  rock,  which  is  mineralized 
with  quartz,  pyrite,  arsenopyrite  and  galena.  Rich  sulphides 
of  silver  have  been  met  in  the  upper  portions.  The  Alta  mine 
near  Wickes  was  located  on  a  vein  in  andesite.  The  Ruby 
mine,  on  Lowland  Creek,  appears  to  be  a  chimney  of  boulders 
of  rhyolite,  which  are  coated  with  gold-bearing  silver-sul- 
phides. It  resembles  the  Bassick  mine  of  Colorado  (2.09.20) 
in  geological  relations.  One  of  the  largest  mines  yet  opened 
in  the  county  is  the  Elkhorn.  The  ore-deposits  resemble  the 
'^saddles"  of  the  Bendigo  Field,  Victoria,  Australia.*    They 

^  For  these  notes  the  writer  is  especially  indebted  to  Mr.  W.  H.  Weed, 
of  the  U.  S.  Geological  Survey.  See  also  S.  F.  Emmons,  Tenth  Census, 
XIII.,  97.  The  northeastern  portion  of  Madison  County  has  been  mapped 
by  A.  C.  Peale— Three  Forks  Folio,  U.  S.  Geol.  Survey-  -by  whom  are  also 
given  notes  on  the  mines      Rec. 

^  R.  Pearce,  "Notes  on  the  Occurrence  of  Tellurium  in  an  Oxidized 
Form  in  Montana,"  Proc.  Colo.  Sci.  Soc,  November  2,  1896. 

^  S.  F.  Emmons,  Tenth  Census,  XIII.,  97.  R.  W.  Barrell,  "The  Min- 
eral Formation  at  the  Golden  Leaf  Mines,"  Eng.  and  Min.  Jour.,  July  17, 
1897,  64. 

*  E.  J.  Dunn,  "Quarterly  Report  to  the  Mining  Department  of  Victoria," 
December,  1888.  T.  A.  Rickard,  "  The  Bendigo  Gold  Field,"  Trans.  Amer. 
Inst  Min  Eng.,  XX.,  463,  1891. 


318 


KEMP'S  ORE  DEPOSITS. 


occur  along  the  contact  of  Cambrian  slate,  and  underlying  lime- 
stone, and  are  replacements  of  the  limestone  at  the  crests  of 
shattered  anticlines.  The  ores  are  silver  sulphides  in  a  quartz 
gangue,  but  with  occasional  large  bunches  of  galena,  and  very 
beautiful  crystals  of  calamine.^ 

2.10.09.  Silver  Bow  County.  The  mines  around  Butte  are 
the  chief  if  not  the  only  ones  of  the  county.  Their  general  ge- 
ology and  distribution  will  be  found  described  under  *' Copper" 
— in  connection  with  the  copper  veins,  and  a  map  is  there  given 
of  the  local  geology.  The  silver  veins  surround  the  copper 
ones  on  the  north,  southwest  and  west.     Their  geological  rela- 


•J 


\S) 


'^■<^' 


4f  %,  \\\i\ 


a846  6  78'> 

Fig.  124. — Cross  section  af  vein  at  tlie  Alice  mine,  Butte,  Mont.     TJie  width  of 

vein  is  4S)  feet.     After  W.  P.  Blake,  Trans.  Amer.  Inst.  Min.  Eng., 

XVI,  p.  72. 

1.  Granite  country.  2.  Softened  granite  with  small  veins.  3.  Clay  wall  with  decomposed 
granite.  4.  Quartz,  broken  and  seamed.  5.  Clay  and  decomposed  granite.  6.  Quartz  and 
manganese  spar — "■  curly  ore."  7.  Quartz  and  ore—"  hard  vein."  8.  Soft  granite  with  vein- 
ets.    i\  Hard-colored,  hard  granite  of  the  hanging-v  all  country. 

tions  and  character  are  much  the  same,  but  in  mineralogy  and 
distribution  they  are  different.  The  silver  veins  occur  both  in 
the  basic  (Butte)  granite,  and  in  the  acidic  (Bluebird)  granite. 
They  contain  as  gangue  in  addition  to  quartz,  manganese  com- 
pounds, rhodonite  and  rhodochrosite.  The  outcrops  of  the 
veins  appear  as  blackened  ledges  of  quartz,  the  stain  being  due 
to  manganese  oxides.  The  ores  are  sulphides  of  silver,  galena, 
blende  and  pyrite,  with  almost   no   copper  minerals   whatso- 

^  The  above  notes  were  chiefly  furnished  by  Mr.  W.  H.  Weed.  See  also 
S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  97.  J.  S.  Newberry,  "On 
Red  Mountain,"  Annals  N.  Y.  Acad.  Sci.,  III.,  p.  251. 


Fig.  122. — Outcrop  of  the  Wabash  silver  lode,  projecting  above  the  granite^ 
Butte,  Montana.    From  a  photograph  by  A.  C.  Beatty,  1896. 


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Fig.  12d.— Weathered  granite,  Butte,  Montana.     The  boulders  are  due  to 

the  rounding  off  of  blocks,  produced  by  joints.     From  a 

photograph  by  J.  F.  Kemp,  1896. 


SILVER  AND  GOLD,   CONTINUED,  319 

ever,  except  along  the  border  between  the  copper  territory  and 
the  silver.  The  veins  display  recognizable  banding  of  ore  and 
gangne.  One  series  of  locations  embracing  the  Moulton,  the 
Alice  and  the  Magna  Charta,  has  been  called  the  Rainbow  lode 
by  J.  E.  Clayton  from  its  crescentic  sweep. 

In  other  respects,  as  regards  faults,  relation  to  the  walls 
and  general  origin,  the  remarks  already  recorded  under  "Cop- 
per" will  hold  good. 

Auriferous  gravels  were  early  washed  in  the  valley  of  Silver 
Bow  Creek,  and  led  to  the  discovery  of  the  deep  veins.  ^ 

2.10.10.  Broadwater  County  has  recently  been  organized,  and 
contains  quartz  veins  in  slates  near  Winston,  and  auriferous 
pyrites  in  shattered  granite  at  the  Diamond  Hill  mines. 
Granite  County,  formerly  a  part  of  Deer  Lodge,  has  important 
mines  near  Phillipsburg.  The  Granite  Mountain  mine  is 
located  on  a  fissure  vein  in  granite,  and  yielded  rich  silver 
ores,  with  considerable  gold.  The  vein  adjoins  sedimentary 
rocks,  which  are  much  metamorphosed  by  the  granite.^ 

2.10.11.  Deer  Lodge  County.  Placers  are  numerous  along 
the  Deer  Lodge  River,  and  auriferous  quartz  veins  are  not 


*  The  Butte  Special  Folio  of  the  U.  S.  Geological  Survey  is  the  best  work 
of  reference.  It  is  by  W.  H.  Weed,  S.  F.  Emmons,  and  Geo.  W.  Tower. 
W.  P.  Blake,  "Silver  Mining  and  Milling  at  Butte,  Mont.,"  Trans. 
Amer.  Inst.  Min.  Eng.,  XVI.,  38.  "Rainbow  Lode,  Butte,  Mont.," 
Idem,  XVI.,  65.  Rec.  R.  G.  Brown,  "The  Ore  Deposits  of  Butte  City," 
Idem,  XXIV.,  543,1894.  Rec.  S.  F.  Emmons,  "Notes  on  the  Geolo- 
gy of  Butte,  Mont.,"  Idem.,  XVI.,  49.  C.  W.  Goodale,  "The  Con- 
centration of  Ores  in  the  Butte  District,  Montana,"  Idem,  XXVI.,  599, 
1896.  Richard  Pearce,  "The  Associations  of  Minerals  in  the  Gagnon 
Vein,  Butte  City,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  63.  E.  D.  Peters, 
Mineral  Resources  of  U.  S.,  1883-84,  p.  374.  E.  G.  Spilsbury,  "Placer 
Mining  in  Montana,"  Eng.  and  Min.  Jour.,  September  3,  1887,  p.  167. 
Rec.  "  Silver  Mines  of  Butte,  Mont.,"  Ibid.,  April  18,  1885,  p.  261.  Wil- 
liams and  Peters,  on  Butte,  Mont.,  Eng.  and  Min.  Jour*.,  March  28,  1885, 
p.  208,     See  also  references  under  Butte  Copper. 

^  H.  M.  Beadle,  "The  Condition  of  the  Mining  Industry  in  Montana  in 
1S92,"  Eng.  and  Min.  Jour.,  February  11,  1893,  p.  123.  W.  H.  Dodds. 
"Granite  Mountain  Mine,"  Colliery  Engineer,  December,  1892.  G.  W. 
Goodale  and  W.  A.  Akers,  "Concentration,  etc.,  with  Notes  on  the  Geol- 
ogy of  the  Flint  Creek  Mining  District,"  Trans.  Amer.  Inst.  Min.  Eng., 
XVIII.,  242,  1890.  Rec.  "The  Granite  Mountain  Mine, "  ^/ig.  and  Min 
Jour.,  December  10,  1887;  November  23.  1889. 


320  KEMP'S  ORE  DEPOSITS. 

lackiDg.     In  the  extreme  eastern  part  are  the  veins  of  the 
Bald  Butte  group  in  slates  and  intrusive  diorite/ 

2.10.12.  Lewis  and  Clarke  County.  The  placer  mines, 
near  Helena  (in  Last  Chance  and  Prickly  Pear  gulches),  were 
the  first  in  the  county  to  attract  attention.  They  were  found 
by  the  prospectors  who  spread  through  the  Rocky  Mountains 
as  the  California  gold  diggings  gave  out.  Since  then  many 
auriferous  quartz  veins  in  granite  and  slates  have  been  devel- 
oped. Some  twenty  miles  north  of  Helena,  in  the  town  of 
Marysville,  is  the  Drumlummon  group  of  veins,  which  carry 
refractory  silver  and  gold  ores,  in  a  quartz  gangue,  on  the  con- 
tact between  a  diorite  boss  and  the  surrounding  metamorphic 
schists.  There  are  also  other  veins  in  the  granite.  Dikes  of 
intrusive  rocks  occur  associated  with  the  ore  bodies.^ 

2. 10. 13.  Meagher  County  contains  the  Castle  Mountain  min- 
ing district,  once  the  heaviest  producer  of  silver-lead  ores  in 
the  State.  The  Castle  Mountains  embrace  a  geological  section 
from  and  including  the  Algonkian  to  the  present.  Intrusions  of 
granite,  diorite,  various  porphyritic  rocks  and  surface  flows  of 
considerable  petrographical  range  are  likewise  present.  In  the 
closing  years  of  the  decade  of  the  eighties  discoveries  were 
made  of  silver-lead  ores  in  the  Carboniferous  limestones,  in  the 
neighborhood  of  intrusions  of  porphyry  and  sometimes  in  the 
contact  zones.  After  several  years  of  activity,  which  was 
maintained  despite  the  remoteness  from  rail,  the  low  price  of 
silver  caused  their  shutting  down.  The  Cumberland  mine,  the 
largest  opened,  formed  a  chimney  or  tubular  mass  in  the  lime- 
stone, and  was  proved  for  over  500  feet  in  depth.  Copper- 
bearing  veins  were  also  found  in  the  Belt  shales  of  the  Algon- 
kian in  the  northern  portion  of  the  area.^ 

In  the  extreme  northern  portion  of  Meagher  County,  and 
near  the  line  with  Cascade  County,  the  two  mining  districts  of 

*  R.  G.  Brown,  ''Georgetown  Mining  District,"  Eng.  and  Min.  Jour., 
October  13,  1894,  345.  E.  G.  Spilsbury,  "Placer  Mining  in  Montana," 
Ibid.,  September  3,  1887,  p.  167. 

^  J.  E.  Clayton,  "The  Drumlummon  Group  of  Veins,"  etc.;  Eng.  and 
Min.  Jour.,  August  4  and  11,  1888,  pp.  85,  106.  S.  F.  Emmons,  Tenth 
Ce7isus,  Vol.  XIII.,  p.  97.  L.  S.  Griswold,  "The  Geology  of  Helena,  Mont., 
and  Vicinity,"  Jour,  of  the  Assoc.  Eng.  Soc.,  XX.,  January  1898. 

^  Weed  and  Pirsson,  "The  Castle  Mountain  District,  Montana,"  Bull. 
139,  U.  S.  Geol.  Survey,  1896. 


SILVER  AND  GOLD,   CONTINUED.  321 

Neihart  and  Barker  are  located  in  the  Little  Belt  Mountains, 
but  their  outlets  are  to  the  north  at  Great  Falls.  At  Neihart 
there  is  a  series  of  fissure  veins  running  north  and  south,  in 
metamorphic  gneisses  and  schists  which  are  cut  by  diorite. 
The  veins  are  narrow  and  barren  in  the  dark  colored  gneisses 
and  the  diorite,  but  carry  large  bodies  of  galena,  with  zinc- 
blende  and  pyrite  in  the  feldspathic  gneiss.  The  vein  filling 
is  replaced  and  altered  country  rock  with  quartz  seams  in  it. 
The  quartz  seams  in  some  mines  contain  much  polybasite, 
pyrargerite  and  chalcopyrite,  carrying  very  high  values  in  gold 
and  silver.  Dikes  and  larger  intrusions  of  quartz-porphyry 
also  occur,  but  are  unfavorable  to  the  veins,  as  in  them  the  lat- 
ter split  up  and  become  barren,  except  within  a  hundred  feet  of 
the  surface.  At  Barker  the  ores  are  chiefly  silver- bearing 
galena  and  occur  along  the  contact  between  granite-porphyry 
and  limestone.^ 

2.10.14.  Cascade  County  contains  important  coal  mines  and 
the  smelting  center  at  Great  Falls.  In  Missoula  County  at 
Quigley,  southeast  of  Missoula, there  is  auriferous  pyrite  in  slates 
of  Lower  Cambrian  or  Algonkian  age  (W.  H.  Weed).  At 
Iron  Mountain  operations  were  formerly  carried  on,  but  are 
now  suspended,  and  there  are  various  minor  camps  throughout 
the  country.^ 

The  latter  statement  applies  as  well  to  Ravalli  County  in  the 
south.  Within  the  limits  of  the  Lewis  and  Clarke  Timber  Re- 
serve there  are  occasional  intrusions  of  porphyritic  rocks  in  the 
Algonkian  or  Lower  Cambrian  shales  and  limestones,  and  in 
the  neighborhood  of  the  igneous  rocks  copper  deposits  are 
found. ^  The  Reserve  lies  in  several  counties.  Similar  depos- 
its are  found  amid  the  high  peaks  of  the  Continental  Divide  <5n 
the  so-called  '*Roof  of  the  Continent,'*  along  the  line  of  Flat- 
head and  Teton  counties.* 

^  The  XX.  Ann.  Rep.  of  the  Director  of  the  U.  S.  Geol.  Survey,  which 
will  probably  be  issued  in  1901,  will  contain  a  paper  by  W.  H.  Weed,  on 
the  ' '  Mining  Districts  of  the  Little  Belt  Mountains. "  The  above  notes 
have  been  kindly  furnished  by  Mr.  Weed,  in  advance  of  his  longer  paper. 

"  F.  D.  Smith,  "The  Cedar  Creek  Placers,"  Eng.  and  Min.  Jour.,  Feb- 
ruary 4,  1899,  143. 

^  R.  H.  Chapman,  "Geological  Structure  of  the  Rocky  Mountains  with- 
in the  Lewis  and  Clarke  Timber  Reserve."  Read  at  the  New  York  meet- 
ing, Amer.  Inst.  Min.  Eng.,  February,  1899. 

*  G.  E.  Culver,  "  Notes  on  a  little  known  Region  in  Northwestern  Mon- 
tana," Trans.  Wis.  Acad,  of  Science,  Arts  and  Letters,  VIII.,  187,  1891. 


322  KEMP'S  ORE  DEPOSITS. 

2.10.15.  In  Flathead  County,  in  the  extreme  northwestern 
corner  of  the  State,  on  Libbey  Creek  and  the  Yak  River,  there 
have  been  recently  discovered  large  deposits  of  gold-bearing 
pyrrhotite  in  diorite  similar  in  geological  relations  to  the  ores 
subsequently  described  at  Rossland,  B.  C.  Tellurides  were  re- 
ported some  years  ago  at  a  little  camp  called  Sylvanite. 

2.10.16.  Cboteau  and  Fergus  Counties.  Very  great  scien- 
tific interest  and  considerable  economic  importance  are  attached 
to  several  new  districts,  that  have  been  opened  up  in  the  small 
outlying  groups  of  mountains,  which  rise  from  the  plains  well 
to  the  east  of  the  main  chain  of  the  Rocky  Mountains.  They 
are  all  characterized  by  intrusions  of  igneous  rocks,  rich  in 
alkalies,  such  as  syenite-porphyries,  phonolites,  and  related 
types.  These  are  the  rocks  which  are  present  in  the  Black 
Hills,  where,  in  the  Potsdam  sandstones,  tellurides  of  gold 
occur,  associated  with  fluorite;  and  at  Cripple  Creek,  Colo., 
where  the  ore  and  gangue  are  the  same.  Weed  and  Pirsson 
have  described  the  geology  of  the  Little  Rocky  Mountains. 
In  the  central  portion  of  a  roughly  elliptical  area  of  upheaval, 
crystalline  Archean  schists  are  seamed  by  intrusions  of  granite- 
porphyry,  syenite-porphyry,  and,  near  Landusky,  by  phonolite, 
Cambrian,  Siluro-Devonian,  Carboniferous  and  Jurassic  strata 
mantle  the  edges.  The  ore  and  gangue  are  found  coating  the 
fragments  of  decomposed  porphyry,  but  do  not  seem  to  lie  along 
well-defined  veins. ^  The  parallelism  with  Cripple  Creek  is  close. 
The  Little  Rockies  are  situated  in  Choteau  County,  180  miles 
east  of  the  main  Rockies.  The  Judith  Mountains,  in  Fergus 
County,  nearer  the  central  part  of  the  State,  are  larger,  but  of 
much  the  same  geological  structure.  A  core  of  syenite-por- 
phyry is  surrounded  by  the  sediments,  which  have  been  up- 
lifted by  its  intrusion  as  a  laccolite.  It  is  associated  with 
phonolite.  Where  the  igneous  rocks  cut  the  sedimentaries 
and  especially  along  their  contacts  with  a  white  Carboniferous 
limestone  free  gold  and  tellurides  with  associated  fluorite  are 

*  W.  H.  Weed,  "Ore  Deposits  of  the  Little  Rocky  Mountains,"  ^ngr. 
and  Min.  Jour.,  May  2,  1896,  423.  Weed  and  Pirsson,  "Geology  of  the 
Little  Rocky  Mountains,"  Jour,  of  Geol,  IV.,  399,  1896.  See  also  E.  S. 
Dana,  in  Col.  Wm.  Ludlow's  "Report  of  a  Reconnaissance  from  Carroll,. 
Montana,  to  the  Yellowstone  National  Park,"  War  Dept.,  Washington. 
1876,  127. 


SILVER  AND  GOLD,   CONTINUED.  323 

found  in  the  brecciated  limestone/     Lewiston  and  Maiden  are 
the  chief  settlements. 

The  Sweet  Grass  Hills  near  the  Canadian  line  in  Chotean 
County  are  similar  in  geology  and  have  been  the  scene  of  some 
placer  mining.  Other  groups  of  mountain,  such  as  the  High 
wood  and  Bearpaw  ranges,  which  are  piles  of  volcanic  lavas 
and  tuffs,  are  known  to  contain  richly  alkaline,  igneous  rocks, 
but  ore  bodies  have  not  yet  been  reported.^ 

IDAHO. 

2.10.17.  G^eo^ogf^. —The  southern  part  of  the  State  extends 
into  the  alkaline  deserts  of  the  Great  Basin,  and  is  dry  and 
barren.  North  of  this  is  the  Snake  River  Valley,  which  is 
filled  by  a  great  flood  of  recent  basalt,  which  stretches  from  the 
Wyoming  line  nearly  across  the  State.  North  of  the  Snake 
River  a  large  area  of  granite  appears  in  the  western  portion, 
and  contains  many  mines.  Extensive  deposits  of  gravel  also 
occur.  Metamorphic  rocks  and  Paleozoic  strata  largelj^  consti- 
tute the  northern  portion  of  the  State,  and  are  penetrated  by 
many  igneous  intrusions.  The  eastern  part  lies  on  the  western 
slopes  of  the  Bitter  Root  Mountains,  whose  general  geology 
was  outlined  under  Montana.  The  geology  of  Idaho  has  been 
but  slightly  studied,  and  the  few  reliable  records  have 
resulted  from  the  scattered  itineraries  of  Hay  den's  survey,  iso- 
lated mining  reports,  and  the  collections  of  the  Tenth  Census,^ 

*  W.  M.  Courtis,  "Gold  in  Fossiliferous  Limestone  in  the  Judith  Moun- 
tains," Eng.  and  Mm.  Jour.,  June  28,  1884,  478.  H.  C.  Freeman,  "The 
Ammon  Mines,  Fergus  Co.,  Mont.,"  Idem,  May  4,  1895,  416.  W.  H.  Weed, 
"Mineral  Resources  of  the  Judith  Mines,"  Idem,  May  23,  1896,  496. 
Weed  and  Pirsson,  "  Geology  and  Mineral  Resources  of  the  Judith  Moun- 
tains," XVIII  Ann.  Rep.  U.  S.  Geol.  Survey,  Part  III.,  p.  437. 

'  Weed  and  Pirsson,  ' '  High  wood  Mountains  of  Montana, "  Bull.  Geol. 
Soc.  Amer.,  YL,  389.  "Bearpaw  Mountains, " ^mer.  Jour.  /Sci.,  May,  1896, 
283  ;June,  351;  August,  136;  September,  188. 

""  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  52.  F.  H.  Bradley,  Hayden's 
Survey,  1S72,  p.  208.  G.  H.  Eldredge,  "A  Geological  Reconnaissance 
across  Idaho,"  XVI  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey,  II.,  217.  F.  V. 
Hay  den,  Ann.  Rep.,  1871,  pp.  1,147;  1872,  p.  20.  W.  Lindgren,  "Mining 
Districts  of  the  Idaho  Basin  and  the  Boise  Ridge,  Idaho,"  XVIII  Rep.  Dir. 
U.  S.  Geol.  Survey,  Part  III.,  p.  617.  Pec.  Boise  Folio,  ?7.  S.  Geol.  Survey. 
Rec.  Other  folios  are  in  preparation.  An  extended  paper  by  Lindgren 
is  in  press  for  the  XX.  Ann.  Report  of  the  U.  S.  Geol.  Survey,  which  will 


324  KEMP'S  OliE  DEPOSITS. 

but  it  is  now  receiving  much  attention  from  tiie  U.  S.  Geologi- 
cal Survey. 

2. 10. 18.  The  extreme  northern  portion  of  Idaho  has  assumed 
increasing  interest  in  recent  years  on  account  of  the  notable 
mining  developments  in  the  neighboring  parts  of  British 
Columbia,  but  discoveries  are  still  largely  in  the  nature  of 
prospects.  Kootenai  County  forms  the  so-called  ''pan-handle," 
and  in  it  some  gold -quartz  veins  and  placers  are  known.  The 
great  silver-lead  mines  of  Coeur  d'Alene  in  Shoshone  Count}' 
have  already  been  described  (2.08.22).  Some  scattered  mining 
camps  occur  in  Talah,  Nez  Perces  and  Idaho  counties  to  the 
south.  In  the  extreme  southern  tongue  of  Idaho  County  is  the 
Sheep  Mountain  district.  The  country  rock  is  granite,  with 
associated  schists  and  slates  in  larger  or  smaller  masses,  often  as 
inclusions.  There  are  also  dikes  of  quartz-porphyrites  and 
diorite  porphyrites.  The  ores  are  impregnations  of  zones  of 
the  schists  or  slates,  with  silver- bearing  galena,  and  antimonial 
and  arsenical  sulphides.^ 

2.10.19.  In  Lemhi  County  is  the  famous  old  gold  diggings 
at  Leesburg,  which  had  a  large  population  in  1859 --60,  but 
which  are  now  practically  abandoned  except  for  an  extensive 
hydraulic  workings  at  California  Bar,  further  down  Napias 
Creek.  In  the  western  side  of  Lemhi  County  is  Yellow  Jacket, 
with  gold  ores  associated  with  a  complex  series  of  intruded 
Igneous  rocks,  in  metamorphic  schists.^  The^  ores  lie  along 
fractured  zones  and  in  the  Columbia  properties  are  chiefly  gold- 
bearing  chalcopyrite.  H.  H.  Armstead,  Jr.,  informs  the  writer 
that  tellurides  have  also  been  detected.  In  the  Yellow  Jacket 
mines  the  ore  is  free-milling  quartz.  In  northeastern  Lemhi 
County  is  Gibbonsville,  where  auriferous  pyrite  occurs  in 
quartz  veins  in  slates.^ 

2.10.20.  Custer  County  lies  south  of  Lemhi  and  contains 
several  well-known  mines.     The  Ramshorn  is  in  metamorphic 

probably  be  issued  in  1901.  J.  S.  Newberry,  '*  Notes  on  the  Geology  and 
Botany  along  the  Northern  Pacific  Railroad,"  Annals,  N.  Y.  Acad.  Sci., 
III.  252.  Raymond's  Reports  on  Mineral  Resources  West  of  the  Rocky 
Mountains.     O.  St.  John,  Hayden's  Survey,  1877,  p.  323;  1878,  p.  175. 

\  G.  H.  Eldredge,  XVI.  Ann.  Rep.  U.  S.  Geol.  Survey.     Part  II.,  p.  258. 

'  G.  H.  Eldridge,  "A  Geological  Reconnaissance  Across  Idaho,"  XVL 
Ann.  Rep.  U.  S.  Geol.  Survey,    II.,  259. 

»  B.  MacDonald,  Eng.  and  Min.  Jour.,  October  3,  1896,  319. 


Fig.  125. — The  old  gold  diggings  on  Napias  Creek,  Leeshurg,  Idaho,  illus 

trating  an  abandoned  placer  camp.     From  a 

photograph  by  J.  F.  Kemp,  1896. 


Fig.  136.— Ftew  on  Napias  Creek,  below  California  Bar,  Idaho,  after  a 
freshet.  From  a  photograph  by  J.  F.  Kemp,  1896. 


SILVER  AND  GOLD,   CONTINUED.  325 

slates  on  a  fissure  vein  that  has  rich  chutes  of  high-grade  sil- 
ver ores  in  a  siderite  gangue.  The  Custer  and  the  Charles 
Dickens  are  farther  west,  near  Bonanza  City,  and  afford  both 
silver  and  gold  in  quartz  gangue  from  veins  in  porphyry. 
Smelting  ores  occur  in  the  region,  and  have  been  used  in  some 
operations  based  on  this  treatment.  Boise  and  Elmore  coun- 
ties, on  the  west  and  southwest  of  Custer,  contain  very  impor- 
tant mining  districts.  Lindgren  has  shown  the  extensive  de- 
velopment of  a  gray,  rather  basic  granite,  having  close  affini- 
ties with  the  quartz-mica-diorites.  It  is  penetrated  by  numer- 
ous dikes  of  porphyries  and  minettes  and  is  covered  by  Tertiary 
lake  beds  and  effusive  rocks.  The  granite  has  suffered  consid- 
erable faulting,  usually  on  a  small  scale,  and  in  a  number  of 
districts  the  fissures  thus  formed  have  been  the  scene  of  ore  de- 
position. Their  general  characters  are  shown  by  Fig.  127. 
They  may  occur  as  single  and  isolated  fissures,  as  parallel 
series,  or  as  lines  of  crushing  with  disjointed  vein  fillings. 
Quartz  is  the  almost  invariable  gangue,  calcite  being  very 
subordinate.  The  metallic  minerals  arepyrite,  gold,  arsenopy- 
rite.  zincblende  and  galena.  These  sulphides  likewise  impreg- 
nate the  wall  rock,  but  they  are  then  low  in  the  precious  metals. 
Silver  is  invariably  present,  and  in  the  Banner  district  in  Elmore 
County,  it  is  the  chief  source  of  value.  At  Atlanta,  likewise  in 
Elmore  County,  the  lode  is  of  quite  extraordinary  size,  being 
known  for  two  and  one-half  miles,  with  an  average  width  of  sev- 
enty-five feet,  and  with  many  spurs.  The  pay  ore  occurs  in  four 
or  five  shoots  in  the  main  vein,  which  are  of  moderate  widths. 
Silver  predominates  over  gold.  In  the  neighborhood  of  the  gold- 
bearing  veins  in  granite,  placers  have  been  and  are  extensively 
operated,  and  indeed,  led  to  the  settlement  of  the  country.  The 
principal  deep- mining  localities  are  the  Idaho  City  belt,  the 
Quartzburg-Grimes  Pass  belt,  both  within  the  depression  known 
as  the  Idaho  Basin ;  and  then  in  the  mountains  to  the  west, 
called  the  Boise  ridge,  there  are  the  Neal,  Black  Hornet,  Boise, 
Shaw  Mountain,  Willow  Creek  and  Rock  Creek  districts.^ 

»  J.  E.  Clayton,  "Atlanta  District,"  Trans.  Amer.  Inst  Min.  Eng., 
VI.,  468.  G.  H.  Eldridge,  "  A  Geological  Reconnaissance  Across  Idaho," 
XVL  Ann.  Rep.  U.  S.  Geol.  Survey,  217.  W.  Lindgren,  "  Mining  Districts 
of  the  Idaho  Basin  and  the  Boise  Ridge,  Idaho,"  XVIII,  Idem,  Part  III., 
p.  617.  Rec.  The  Boise  Folio,  U.  S.  Oeol.  Survey.  Rec.  An  important 
paper  may  be  expected  in  the  XX  Ann.  Rep.  of  the  Survey. 


KEMP'S  ORE  DEPOSITS. 


cz: 


'•///'  /  //  W 

/  A^J  '  #' 

'  • 

J//  //  /^'^ 

•^ 

f;     ^/''',^^^~ 

^# 

'/J//        ^^^^''^ 

^    / 

7//^^  ■ 

■•  /  // 

-'/  ^p^\ 

MM. 

M 

mm 


10  feet  6 


El 


Fig.  137. — Sections  to  illustrate  typical  gold  veins  in  the  Boise  granite  region, 
Tdaho.     After  W.  Lindgren,  XVIII.  Ann.  Hep.  U.  S.  Oeol. 
Survey,  Part  III.,  Plate  XC. 

1.  Simple  fissure  vein  on  one  fault  plane,  with  quartz  filling,  which  alone  is  ore.  Wall-rock 
altered,  but  barren.  2.  Complex  fissure  with  four  fault  planes.  Rich  ore  fills  the  long  nar- 
row openings  and  impregnates  adjacent,  altered  wall-rock.  3.  Simple,  narrow,  fissure  vein, 
filled  with  ore  which  also  impregnates  altered  wall-rock.  4.  Complex  fissure  vein,  with  two 
fault  planes.  Intermediate  rock  and  outer  walls  altered,  the  former  also  sheeted.  5.  Irregu- 
larly shattered  zone  between  two  fault  planes.  Intermediate  rock  excessively  altered. 
Quartz  fills  seams  and  cracks.  6.  Quartz  vein  of  rich  ore  along  under  side  of  altered 
porphyry  dike  and  with  branches  into  hanging.    Altered  dike  forms  low-grade  ore. 


SILVER  AND  GOLD,   CONTINUED.  327 

2.10.21.  Alturas  County  contains  one  very  important  silver- 
lead  district,  the  Wood  River,  which  has  been  earlier  referred 
to  (under  Example  32a).  Owyhee  County  forms  the  southwest- 
ern corner  of  the  State.  Apparently  the  same  granite  that  is 
so  prominent  in  Boise  and  Elmore  reappears  from  beneath  the 
intervening  Tertiary  deposits,  and  comes  up  near  Silver  City. 
Still  further  southwest  quartz- porphyry  and  metamorphic  rocks 
are  found  with  dikes  of  basalt.  Gold-quartz  and  high-grade  sil- 
ver ores  are  present.  The  Poorman  Lode  is  famous  for  ruby 
silver  ores.  W.  P.  Blake  mentions  seeing  a  piece  from  this 
mine  at  the  Paris  Exposition  which  weighed  about  200  pounds.* 
It  was  awarded  a  gold  medal.  The  crystal  from  which  it  was 
broken  weighed  500  pounds.^  In  Cassia,  Logan,  Oneida  and 
other  counties  in  the  southern  part,  placers  are  being  or 
have  been  worked,  and  in  Bear  Lake  County,  in  the  southeast 
corner,  salt  and  sulphur  deposits  are  recorded.*  The  gold  of 
the  Snake  River  sands  is  extremely  fine,  and  difficult  to  save. 

^  Amer.  Jour.  Sci.,  ii.,  XLV.,  97. 

^  Raymonds  Reports  on  Mineral  Resources  West  of  t?ie  Rocky  Mountains, 
1868,  p.  533. 

3  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  59.  T.  Egleston,  "The 
Treatment  of  Fine  Gold  in  the  Sands  of  the  Snake  River,  Idaho,"  Trans. 
Amer.  Inst.  Min.  Eng.,  XVIII.,  597.  Raymond's  Reports  on  Mineral  Re^ 
sources  West  of  the  Rocky  Mountains.    Rep.  Dir.  of  the  Mint,  1882,  p.  227. 

* 


CHAPTER  XL 

SILVER  AND  GOLD,  CONTINUED. — THE  REGION  OF  THE  GREAT 
BASIN,  IN  UTAH,  ARIZONA,  AND  NEVADA. 

UTAH. 

2.11.01.  Geology.— 'The  eastern  half  of  Utah,  terminating 
with  the  western  front  of  the  Wasatch,  is  in  the  Colorado 
Plateau,  but  the  western  is  within  the  limits  of  the  Great 
Basin.  The  plateau  portion  consists  largely  of  Mesozoic  strata, 
quite  horizontal  and  more  or  less  carved  by  erosion.  The  east 
and  west  arch  of  the  Uintah  Mountains,  in  the  northern  part, 
has  upheaved  therii,  so  that  where  the  Green  River  has  cut  a 
channel  across,  the  Paleozoic  is  exposed  in  great  strength.  The 
Wasatch  range  rises  with  a  gradual  ascent  from  the  east,  and 
then  terminates  with  a  great  fault  line,  having  a  steep  westerly 
fro^.  This  line  of  weakness  was  developed  in  the  Archean 
and  has  been  a  scene  of  movement  even  to  recent  times.  It  is 
a  very  important  structural  feature.  West  of  the  Wasatch, 
which  is  a  fine  example  of  block-tilting  in  mountain-making, 
the  mountains  belong  to  the  Basin  ranges,  which  are  more  typ- 
ically developed  in  Nevada.  The  Wasatch  section  was  shown 
by  the  Fortieth  Parallel  Survey  to  involve  12,000  to  14,000 
feet  of  the  Upper  Archean,  and  nearly  30,000  feet  of  the  Pale- 
ozoic. In  southern  Utah  the  Triassic  rocks  are  important  and 
contain  some  rich  mines.  ^ 

»  G.  F.  Becker,  Tenth  Census,  XIII.,  38.  Whitman  Cross,  "The  Lacco- 
litic  Mountain  Groups  of  Colorado,  Utah  and  Arizona,"  XIV.  Ann.  Rep. 
U.  S.  Geol.  Survey,  Part  II.,  165.  C.  E.  Dutton,  Report  on  the  High  Pla- 
teaus of  Utah,  Washington,  1880.  S.  F.  Emmons,  "Origin  of  Green 
River,"  Science,  VI.,  19,  1897.  Sir.  A.  Geikie,"  Archean  Rocks  of  the  Wa- 
satch Mountains,"  Amer.  Jour.  Set.,  iii.,  XIX.,  363.  G.  K.  Gilbert,  "Lake 
Bonneville,"  Monograph  I.,  U.  S.  Geol.  Survey,  and  II.  Ann.  Rep.,  169-300. 


SILVER  AND  GOLD,   CONTINUED.  dW 

2. 11.02.  The  greater  number  of  the  Utah  mines  are  for  lead- 
silver  ores,  and  have  been  mentioned  under  *' Lead- 
silver."  The  northwestern  county,  Box  Elder,  is  in  the  alka- 
line desert  region  of  the  Great  Basin.  The  mining  districts 
occur  in  the  central  part  of  the  State,  in  the  Wasatch  and 
Oquirrh  mountains,  and  are  also  found  in  the  extreme  south- 
west. 

2.11.03.  Ontario  Mine.  Nearly  east  of  Salt  Lake  City,  in 
Summit  County,  is  the  Ontario  mine,  a  vein  from  four  to 
twenty-three  feet  wide  (averaging  eight  feet),  in  quartzite,  but 
extremely  persistent,  being  opened  continuously  for  6,000  feet. 
In  the  lower  working  a  porphyry  dike  has  come  in  as  one  of 
the  walls.  It  is  extensively  altered  by  f umarole  action  to  clay. 
The  best  parts  of  the  mine  have  quartzite  walls.  The  ores 
consist  of  galena,  gray  copper,  silver  glance,  blende,  etc. 
The  Ontario  vein  extends  through  a  number  of  claims  and  at 
least  one  other  important  vein  is  known,  the  Daly  West,  which 
however,  has  one  wall,  limestone.  Its  product  and  the  latter 
developments  on  the  Ontario  have  changed  the  camp  to  a  lead- 
silver  producer.^ 

2.11.04.  The  lead-silver  veins  of  Bingham  Canon,  in  Salt 
Lake  County,  have  already  been  mentioned.     Reference  may 

"The  Ancient  Outlet  of  the  Great  Salt  Lake,"  Amer.  Jour.  Sci.,  iii.,  XV., 
256;  XIX.,  341;  see  also  A.  C.  Peale,  Ibid.,  XV.,  439.  "The  Henry 
Mountains,"  Washington,  1877.  R.  C.  Hills,  "  Types  of  Past  Eruptions  in 
the  Rocky  Mountains,"  Proc.  Colo.  Sci.  Soc,  IV.,  14.  International  Geo- 
logical Congress,  Washington  meeting,  1891,  Guide  Book  to  the  Rocky 
Mountains.  J.  D.  Irving,  "  The  Stratigraphical  Relations  of  the  Browns' 
Park  Beds,  Utah,"  Trans.  N.  Y.  Acad.  Sci.,  XV.,  252.  Hague,  King,  and 
Emmons,  Fortieth  Parallel  Survey,  Vols.  I.  and  II.  O.  C.  Marsh,  "  On  the 
Geology  of  the  Eastern  Uintah  Mountains,"  Amer.  Jour.  Sci.,  iii.,  I.,  191. 
H.  Montgomery,  "Volcanic  Dust  in  Utah  and  Colorado,"  Science,  I.,  656, 
1895.  B.  Silliman,  "  Geological  and  Mineralogical  Notes  on  Some  of  the 
Mining  Districts  of  Utah  Territory,"  ^mer.  Jour.  /Sci,  iii..  III.,  195.  G. 
O.  Smith,  "Igneous  Phenomena  in  the  Tintic  Mountains,  Utah,"  Science, 
VII.,  502,  1898.  J.  Walther,  "The  North  American  Deserts,"  Nat.  Geog. 
Magazine,  IV.,  163.  Wheeler,  Gilbert,  Lockwood  and  others,  on  Western 
Utah,  Wheeler's  Survey,  Rep.  Prog.,  1869-71-72.  Idem,  Final  Reports,  III. 
*  T.  J.  Almy,  "History  of  the  Ontario  Mine,  Park  City,  Utah,"  Trans. 
Amer.  Inst.  Min.  Eng.,  XVI.,  S5.  "The  Ontario  Mine,"  Eng.  and  Mm. 
Jour.,  May  28,  1881,  p.  365.  D.  B.  Huntley,  Tenth  Census,  Vol.  XIII.,  p. 
438.  H.  L.  J.  Warren,  "The  Daly  West  Mine.  Park  City,  Utah,"  Eng 
and  Min.  Jour.,  October,  14,  1899. 


330 


KEMP'S  ORE  DEFOSITS. 


again  be  made  to  the  great  bed-veins  of  gold  quartz  associated 
with  them.  Ophir  Canon  and  Dry  Canon,  in  Tooele  County, 
and  the  Tintic  district,  in  Juab  County,  have  also  been  de- 
scribed. In  addition  to  the  smelting  ores,  others  have  been 
treated  by  milling.  Quite  recently  interest  has  been  directed 
to  the  mines  of  the  Camp  Floyd  district,  of  which  Mercur  is 
the  chief  town.  Rich  deposits  of  gold  ores,  formerly  refrac- 
tory, have  yielded  to  the  cyanide  process,  and  have  given  a 
new  and  large  lease  of  lite  to  a  district  that  was  abandoned 
years  ago,  after  having  had  a  short  career  as  a  silver  producer. 
Mercur  is  situated  in  the  southern  end  of  the  Oquirrh  Moun- 
tains, in  a  valley  known  as  Lewiston  Canon.  A  thick  series 
of  Carboniferous  limestones  and  very  subordinate  shales  has 


S  e-g;     S>     Gulch 


8.66  30  W. 


i§        ll 

~  B  Tremont  j^  ^ 

14     Hin    II 


Va. 


-  "tdwef  XTmestoi 


Great  Blue 
Limestone 
lower  inter- 
calated Series 
Lower 


SECTION  E-E. 

Fig.  128. — Geological  cross- sections  at  Mercur,  Utah,  reduced  from  colored  ones 

by  J.  E.  Spurr;  XVI.  Ann.  Rep.  Dir.  U.  S.  Geol.  Surmy,  Plate 

XXVII.     The  sections  cut  each  other  at  right  angles. 


been  folded  into  a  low  anticline,  as  shown  in  Fig.  128,  whose 
axial  crest  is  also  folded ,  so  that  the  beds  constitute  a  Ioav  dome 
or  swell.  One  great  stratum  of  limestone  has  been  intruded 
by  an  interstratified  sheet  of  quartz-porphyry,  locally  called 
the  Eagle  Hill  porphyry,  which  at  the  most  productive  mines 
has  split  into  three  thin  sheets,  each  150  feet  or  less  from  its 
neighbor.  At  some  time  after  the  intrusion,  ore-bearing  circu- 
lations percolated  along  the  lowest  sheet  and  impregnated  the 
limestone  for  a  zone,  usually  10  to  20  feet  thick,  but  reaching 
even  50  feet  or  more,  with  silver-bearing  minerals  in  a  gangue 
of  cherty  quartz.  Where  mined  the  silver  was  present  in  thin 
films  of  the  chloride  coating  fragments  of  the  chert  and  lime- 


SILVER  AND  GOLD,   CONTINUED. 


331 


stoDe.  Associated  metallic  minerals  are  few.  Stibnite  is 
known,  and  pyrite  has  been  detected  with  the  microscope.  Car- 
bonates of  copper  have  been  noted.     As  gangue  minerals  cal- 


QUAETZ-PORPUYRY  ORE  FRESH  LIMESTONE 

(Altered)  (Altered  limestone} 

Fig.  129. — Diagram  showing  relations  of  ore  to  fault  in  Tunnel  No.  3,  Marion 

Mine,  Mercur,  Utah.     Scale  ^0  feet  to  the  inch.     After  J.  E.  Spurr, 

XVI.  Ann.  Rep.  U.  S.  Geol.  Survey,  430. 


of 
Tunnel 


QUAKTZ-PORPHYRT 

(Altered  ) 


ORE 

(Altered  limestone, 
containing  bowlders 
of  decomposition.) 


FRESH  LIMESTONB 


Fig.  130, — Section  along  the  (leyser  mine  tunnel,  Mercur,  Utah.    After  J.  E. 
Spurr,  XVI  Ann.  Rep.  V.  S.  Geol.  Survey,  422, 

cite  and  barite  are  next  to  chert  in  abundance.  Spurr  favors 
heated  waters  as  the  vehicles  of  the  ore.  Long  after  the  silver 
ores  had  been  deposited  the  gold  series  were  formed,  probably 
as  tellurides,  along  the  contact  of  the  next  overlying  sheet  of 


332  KEMP'S  ORE  DEPOSITS. 

porphyry.  They  are  now  found  where  this  sheet  is  cut  by  a 
series  of  small  northeast  fissures  in  the  limestone,  which  fis- 
sures are  thought  with  great  reason  by  Spurr  to  have  been  the 
conduits  through  which  the  ores  were  introduced.  The  gold  in 
the  oxidized  ores  is  in  some  condition  that  is  readily  soluble  in 
potassium  cyanide,  but  it  is  uncertain  what  that  state  is.  Re- 
algar and  occasionally  cinnabar  are  associated  with  it.  In  the 
unoxidized  ores  pyrites  are  abundant,  but  the  gold  is  but 
slightly  attacked  by  the  cyanide.  It  is  thought  to  have  been 
deposited  as  a  telluride.  The  ores  average  about  ten  dollars 
per  ton.  The  region  is  poorly  supplied  with  water,  and  all  the 
springs  are  carefully  utilized.  R.  C.  Hills, ^  in  the  paper  cited 
below,  explained  the  ores  as  introduced  through  a  series  of  fis- 
sures which,  now  filled  with  calcite,  penetrate  to  the  chutes. 
J.  E.  Spurr, ^however,  regards  the  open  fissures  along  which  the 
chutes  extend,  as  the  conduits,  and  favors  a  vaporous  or  fuma- 
rolic  method  of  introduction.  A  laccolite  of  igneous  rock  at 
some  unknown  point  below  is  suggested  as  the  source  of  the 
vapors.^ 

Considerable  interest  has  been  directed  of  late  to  the  mines  of 
the  Deep  Creek  district,  on  the  extreme  western  border  of  Utah, 
in  the  Ibapah  range.  Limestones  regarded  by  Blake  as  Car- 
boniferous, and  other  sedimentary  rocks,  have  been  broken 
through  by  great  outflows  of  granite,  andesite,  hypersthene-an- 
desite,  etc.  The  ore  bodies  appear  to  be  contact  deposits  in 
limestone  near  igneous  rocks,  and  carry  much  free  gold.* 

*  R.  C.  Hills,  "Ore  Deposits  of  Camp  Floyd  District,  Tooele  Co.,  Utah,'* 
Proc.  Colo.  Set.  Soc,  August  6,  1894.     Rec. 

^  J.  C.  Spurr,  "Economic  Geology  of  the  Mercur  Mining  District,  Utah," 
with  an  Introduction  by  S.  F.  Emmons.  XVI.  Ann.  Rep.  Dir.  U.  S.  Oeol. 
Survey,  II.,  349.     Rec. 

'Other  papers  on  Mercur  are  the  folio  «^^ing:  R.  C.  Gemmell,  "The 
Camp  Floyd  Mining  District  and  the  Mercur  Mine,  Utah,"  Eng.  and  Min. 
Jour.,  LXIII.,  403,  1897.  A.  Lakes,  "The  Oquirrh  Mountains  or  the  Mer- 
cur Mining  District,  Utah,"  Colliery  Engineer,  XVI.,  243,  1896.  W.  H. 
Moeller,  "The  Mercur  Gold  Deposit  in  the  Camp  Floyd  District,  Utah," 
Eng.  and  Min.  Jour.,  LVII.,  51,  1894.  D.  Maguire,  "Gold  Mines  of 
Mercur,"  Mines  and  Minerals,  XIX.,  81,  130,  1898.  J.  W.  Neill,  "Camp 
Floyd  District,  Utah,"  Eng.  and  Min.  Jour.,  LXI.,  85,  1896. 

*  W.  P.  Blake,  "  Age  of  the  Limestone  Strata  at  Deep  Creek,  Utah,  and 
the  Occurrence  of  Gold," etc.,  Amer  Geol. ,  January,  1892,  p.  47.  Eng.  and 
Min.    Jour.,  February  23,  1892,  p.  253.      S.  F.  Emmons,  Fortieth  Parallel 


^mrl 


Fig.  ISl.— Open  cut,  showing  the  pay-streaJc,  at  Mercur,  Utah.    From  a 
photograph  by  P.  K.  Hudson,  1898. 


Fig.  132. — The  Golden  Gatecyanide  mill,  Mercur  district,  Utah.    From 
a  photograph  by^L.  E.  Biter,  Jr.,  1898. 


SILVER  AND  GOLD,   CONTINUED. 


In  Beaver  County  the  interesting  deposits  of  the  Horn  Sil- 
ver, the  Carbonate,  and  the  Cave  ore  bodies  have  been  men- 
tioned under  Examples  30g,  33a,  and  32&.  The  iron  ore 
bodies  of  Iron  County  will  be  found  under  Example  14.  In 
Piute  County,  near  the  town  of  Marysvale,  around  Mount 
Baldy,  are  a  number  of  mines  with  lead-silver  or  milling  ores 
in  quartz  porphyry  (copper  belt),  or  between  limestone  and 
quartzite  (Deer  Trail,  Green-eyed  Monster,  etc.).  Selenide  of 
mercury  is  found  in  the  Lucky  Boy.^ 

2.11.05.  Example  41.  Silver  Reef,  Utah.  Native  silver, 
cerargerite  and  argentite,  impregnating  Triassic  sandstones, 
and  often  replacing  organic  remains.  These  deposits  were 
earlier  referred  to  under  Example  21,  p.  80.  They  were  dis- 
covered in  1877.  At  Silver  Reef  there  are  two  silver-bearing 
strata  or  reefs,  with  beds  of  shale  between.     Above  the  water- 


Ore 


Runs  Into_ 
barren  rock 


Fig.  133. — Two  sections  of  the  argentiferous  sandstone  of  Silver  lieef,  Utah. 
After  C.  M.  Rolker,  Trans.  Amer.  Inst.  Min.  Eng.,  IX.,  p.  21. 


line  the  ore  is  horn  silver;  below  it  is  argentite.  At  times  it 
replaces  plant  remains;  at  other  times  no  visible  presence  of 
ore  can  be  noted,  although  the  rock  may  afford  $30  to  the  ton. 
The  silver  always  occurs  along  certain  ore  channels,  distributed 
through  parts  of  the  sandstone.  The  origin  of  the  deposits 
has  given  occasion  to  a  vigorous  discussion.  J.  S.  Newberry 
held  that  the  silver  was  deposited  in  and  with  the  sandstone 
from  the  Triassic  sea,  although  it  may  have  been  concentrated 
since  in  the  ore  channels.  F.  M.  F.  Cazin  holds  that  the  or- 
ganic remains  were  deposited  in  and  with  the  sandstone,  and 
that  these  were  the  immediate  precipitating  agents  of  the  ores. 
R.  P.  Rothwell  explained  them  much  as  does  Rolker,  below. 

Survey,  Vol.  II.,  p.  475.     J.  F.  Kemp,  • '  Petrographical  Notes  on  a  Suite  of 

Rocks  Collected  by  E.  E.  Olcott,"  Trans.  N.  Y.  Acad.  Scl,  XI.,  127,  1892. 

*  G.  J.  Brush,  "  On  the  Onofrite,"  etc,  Amer.  Jour.  Sci.,  iii.,  XXI.,  312. 


334  KEMP' 8  ORE  DEPOSITS. 

C.  M.  Rolker,  who  was  for  some  years  in  charge  of  several  of  the 
mines  has  also  written  about  them,  and  is  probably  nearest  to  the 
truth.  Rolker  argues  that  the  impregnation  was  subsequent  to 
the  formation  of  the  sandstone,  and  was  caused  by  the  igneous 
outbreaks  in  the  neighborhood,  and  probably  runs  along  old  lines 
of  partial  weakening  or  crushing  that  afterward  healed  up. 
Eruptive  rocks  are  known  in  the  neighborhood  of  the  ores  both 
in  Utah  and  in  the  Nacemiento  copper  district  of  New  Mexico. 
From  what  we  know  of  ore  deposits  in  general  this  seems  most 
probable.^ 

ARIZONA. 

2.11.06.  Geology. — Arizona  lies  partly  in  the  plateau  re- 
gion, and  partly  in  the  Great  Basin.  The  Basin  ranges  con- 
verge with  the  Rocky  Mountains,  which,  however,  are  chiefly 
in  New  Mexico.  The  uplands  of  the  ranges  are  well  watered 
and  covered  with  timber,  but  the  low-lying  portion  of  the 
Great  Basin  is  an  arid  desert,  and  in  southwestern  Arizona  is 
the  hottest  part  of  the  United  States.  Cretaceous  and  Jura- 
Trias  largely  form  the  plateau  region.  Running  southeast  to 
northwest  is  the  great  development  of  Carboniferous  limestone 
so  often  referred  to  under  ** Copper,"  and  underlying  this  are 
found  Archean  granites,  gneisses,  etc.  A  great  series  of  ore 
deposits  is  ranged  along  this  contact.  In  the  southwest  are 
mountains  of  granites  and  metamorphic  rocks.  The  Territory 
also  contains  vast  flows  of  igneous  rocks,  and  in  the  plateau 
country  between  the  converging  ranges  some  20,000  or  25,000 
square  miles  are  covered  by  them.  The  Grand  Canon  of  the 
Colorado  has  laid  bare  a  magnificent  geological  section  of 
many  thousand  feet,  from  the  Archean  to  the  Tertiary.^ 

*  F.  M.  F.  Cazin,  ' '  The  Origin  of  the  Copper  and  Silver  Ores  in  Triassic 
Sandrock,"  Eng.  and  Min.  Jour.,  December  11,  1880,  p.  381;  April  30,  1881, 
p.  300.  "  The  Silver  Sandstone  Formation  of  Silver  Reef,"  Ibid.,  May  22, 
1880,  p.  351;  January  10,  17,  24,  1880,  pp  25,  48,  79  (Rothwell).  A.  W. 
Jackson,  "Silver  in  Sedimentary  Sandstone,"  i^ep.  Dir.  of  Mint,  1882,  p. 
384,  reprinted  from  Cal.  Acad.  Sci.  J.  S.  Newberry,  "Report  on  the 
Properties  of  the  Stormont  Silver  Mining  Company,"  etc.,  Eng.  and  Min. 
Jour.,  October  23,  1880,  p.  269.  "The  Silver  Reef  Mines,"  Ibid.  January 
1,  1881,  p.  4.  C.  M.  Rolker,  "The  Silver  Sandstone  District  of  Utah." 
Trans.  Amer.  Inst.  Min.  Eng.,  IX.,  21. 

'  "  Central  Arizona,"  Eng.  and  Min.  Jour.,  April  23,  1881,  p.  285.     "  Col 
orado  River  of  the  West,"  review  of  Ives  Expedition,  Amer.  Jour.  Sci.,  ii 


SILVER  AND  GOLD,   CONTINUED.  335 

2.11.07.  Apache  County  is  in  the  northeastern  corner.  In 
the  southern  part  of  the  county  gold  and  silver  ores,  in  veins  in 
limestone,  associated  with  copper  ores,  are  reported,  and  some 
small  placers. 

2.11.08.  Yavapai  County.  Gold  and  silver  ores,  in  quartz 
veins,  in  granite  and  metamorphic  rocks.  The  Black  range 
copper  district  has  already  been  referred  to  under  Example  20e. 

Mohave  County.  Silver  sulphides,  arsenides,  etc.,  and  alter- 
ation products  in  veins  in  granite,  at  times  showing  a  gneissoid 
structure.     Only  the  richest  can  now  be  worked. 

Yuma  County.  Quartz  veins,  with  silver  ores  and  lead  min- 
erals in  metamorphosed  rocks  (gneiss,  slate,  etc.),  or  in  gran- 
ite. 

Maricopa  County  contains  both  Paleozoic  and  Archean  ex- 
posures. The  ore  deposits  lie  mostly  along  the  contact  of  the 
two,  in  granite  or  highly  metamorphosed  strata.  They  are 
usually  quartz  veins,  with  silver  ores  and  copper,  lead,  and 
zinc  minerals.  The  Globe  district,  extending  into  Pinal 
County,  is  the  principal  one.  Mention  has  already  been  made 
of  it  under  "Copper,"  Example  20c. 

Pinal  County  adjoins  Maricopa  on  the  south  and  contains  a 
number  of  important  mines.  They  produce  mostly  silver  ores, 
with  lead  and  copper  associates,  and  some  blende.  The  gangue 
minerals  are  quartz,  calcite,  etc.,  occasionally  manganese  com- 
pounds, and  sometimes,  in  the  granites,  barite.  Limestone,  slate, 
sandstone,  and  quartzite,  as  well  as  granite,  diabase  and  diorite, 
occur  as  wall  rock. 

2.11.09.  Silver  King  Mine.  A  central  mass  or  chimney  of 
quartz,  with  innumerable  radiating  veinlets  of  the  same,  carry- 
ing rich  silver  ores  and  native  silver,  in  a  great  dike  of  feld- 

XXXIII.,  387.  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  44.  C.  E.  But- 
ton, "  The  Physical  Geology  of  the  Grand  Canon  District,"  abstract  of 
Monograph  II.,  Sec.  Ann,  Rep.  Dir.  U.  S.  Geol.  Survey,  49-161 ;  see  also  the 
Monograph.  Patrick  Hamilton,  The  Resources  of  Arizona,  A.  L.  Bancroft 
&  Co.,  San  Francisco,  1884.  B.  Silliman,  "Report  on  Mining  Districts  of 
Arizona,  near  the  Rio  Colorado,"  Eng.  and  Min.  Joi^r.,  August  11,  1877,  p. 
Ill ;  taken  from  Amer.  Jour.  Sci.,  ii.,  XLI.,  289.  C.  D.  Wolcott,  "Permian 
and  Other  Paleozoic  Groups  of  the  Kanab  Valley,  Arizona,"  Amer.  Jour. 
Sci.,  iii.,  XX.,  221.  "  Pre-Carboniferous  Strata  in  the  Grand  Canon  of  the 
Colorado,  Arizona,  "  Amer.  Jour.  Sci.,  December,  1883,  437.  Wheeler's 
Survey,  Vol.  III. ,  and  Supplement. 


336  KEMP'S  ORE  DEPOSITS. 

spar  porphyry,  with  associated  graoite,  syenite  (Blake),  por- 
phyry, gneiss,  and  slates,  all  of  Archean  age.  The  veinlets 
ramify  through  the  strongly  altered  porphyry,  and  form  a 
stockwork,  which  furnished  the  principal  ores.  In  the  region 
are  also  Paleozoic  strata,  w^hose  upper  limestone  beds  are  re- 
ferred by  Blake  to  the  Carboniferous.  The  minerals  at  the 
mine  were  native  silver,  stromeyerite,  argentite,  sphalerite, 
galenite,  tetrahedrite,  bornite,  chalcopyrite,  pyrite,  quartz, 
calcite,  siderite,  and,  as  an  abundant  gangue,  barite. 

Graham  County  contains  the  Clifton  copper  district,  referred 
to  under  Example  20a. 

Cochise  County  is  the  southeastern  county,  and  contains  the 
Tombstone  district,  once  the  most  productive  of  the  precious 
metals  in  the  Territory. 

2.11.10.  Tombstone.  A  great  porphyry  dike  up  to  70  feet 
thick,  faulted  and  altered,  and  carrying  above  the  water  line 
in  numerous  vertical  joints,  or  partings,  quartz  with  free  gold, 
horn  silver,  and  a  little  pyrite,  galenite,  and  lead  carbonate. 
Curiously  enough,  in  the  porphyry  itself  and  far  from  the 
quartz  veins,  flakes  and  scales  of  free  gold  have  been  found, 
evidently  introduced  in  solution.  Ore  also  occurs  along  the 
side  of  the  dike.  There  are  also  other  fissures  parallel  with  this 
principal  dike,  and  still  another  series  crossing  these  and  the 
axis  of  the  great  anticline  of  the  district.  Connected  with 
these  fissure  veins  are  bedded  deposits  in  the  limestone,  along 
the  bedding  planes  or  dropping  from  one  to  another,  appearing 
to  have  originated  by  replacement.  Blake  offers  two  explana- 
tions of  the  first- mentioned  dike  deposit — either  that  the  dike 
itself  held  the  precious  metals,  or  that  thej^  came  from  the  pyrite 
of  the  adjoining  strata.  Several  other  mining  districts  of  less 
note  occur  in  the  county.  The  important  copper  deposits  of 
the  Bisbee  region  have  already  been  mentioned  under  Example 
20/.  The  most  productive  mine  of  the  territory  for  the  last 
year  or  two  has  been  the  Pearce  at  the  town  of  the  same  name, 
but  operated  by  the  Commonwealth  Co.  It  is  a  quartz  vein 
as  5^et  productive  of  oxidized  ores  containing  silver  and  gold. 

2.11.11.  Pima  County  is  the  central  county  of  the  southern 
tier,  and  has  Tucson  as  its  principal  city.  There  are  numbers 
of  mines  of  the  precious  metals,  and  a  few  less  important 
copper  deposits. 


SILVER  AND  GOLD,   CONTINUED.  337 

Yuma  County,  in  the  southwestern  corner,  has  some  mines 
along  the  Colorado  River,  on  quartz  veins  in  metamorphosed 
rocks,  containing  silver  and  lead  minerals/  The  Fortuna  mine 
is  at  present  the  chief  producer. 

NEVADA. 

2.11.12.  Geology. — Nevada  lies  almost  entirely  in  the 
Great  Basin,  only  the  western  portion  heing  in  the  Sierras. 
The  surface  is  thus  largely  formed  by  the  dried  basins  of 
'former  great  lakes,  principally  Lakes  Lahontan  and  Bonne- 
ville. A  large  number  of  ranges  extend  north  and  south 
through  the  State,  known  collectively  as  the  Basin  ranges. 
They  have  been  formed  by  block  tilting  on  a  grand  scale,  and 
present  enormously  disturbed  strata.  The  geological  sections 
exposed  are  of  surpassing  interest  (cf.  Example  36),  and  show 
Archean  and  Paleozoic  in  great  thickness.  In  these  mountains 
are  found  the  mining  districts,  while  between  them  lie  the  alka- 
line plains.^ 

^  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  44.  G.  H.  Birnie,  'Castle 
Dome  District,"  Wheeler's  Survey,  1876,  p.  6.  W.  P.  Blake,  "The  Geology 
of  Tombstone,  Arizona,"  Amer.  Inst.  Min.  Eng.,  X.,  334;  Eng.  and  Min. 
Jour.,  June  24,  1882,  p.  328;  The  Silver  King  Mine,  a  short  monograph, 
New  Haven,  March,  1883.  Rec.  See  also  Eng.  and  Min.  Jour. ,  April  28, 
1883,  p.  238.  J.  F.  Blandy,  "The  Mining  Region  around  Prescott,  Ariz.," 
Trans.  Amer.  Inst.  Min.  Eng.,  XI.,  286;  Eng.  and  Min.  Jour.,  July  21, 
1883.  "On  Tombstone,  Arizona,"  Ibid.,  May  7,  1881,  p.  316;  March  18, 
1882,  p.  145.  "  Silver  in  Arizona,"  General  Review,  Eng.  and  Min.  Jour., 
September  21  and  25,  1880,  pp.  172,  203.  "Central  Arizona,  '  Ibid.,  April 
23,  1881,  p.  285.  O.  Loew,  "Hualapais  District,"  Wheeler-'s  Survey,  1876, 
p.  55.  B.  Silliman,  "  Report  on  the  Mining  District  of  Arizona  near  the 
Rio  Colorado,"  Amer.  Jour.  Sci.,  ii.,  XLI.,  289;  see  also  Eng.  and  Min. 
Jour.,  August  11,  1877,  p.  111.  Raymond's  Reports  and  those  of  the  Di- 
rector of  the  Mint  contain  notes  on  the  Arizona  mines. 

""  J.  Blake,  "The  Great  Basin,"  Proc.  Cal.  Acad.  Sci.,  IV.,  275;  Amer. 
Jour.  Sci.,  iii.,  VI.,  59.  W.  P.  Blake,  "  On  the  Geology  and  Mines  of  Ne- 
vada" (Washoe  Silver  Region),  Quar.  Jour.  Geol.  Sci.,  Vol.  XX.,  p.  317. 
H.  G.  Clark,  "Aurora,  Nevada:  A  Little  of  its  History,  Past  and  Present," 
School  of  Mines  Quarterly,  III.,  133.  G.  K.  Gilbert,  "A  Theory  of  the 
Earthquakes  of  the  Great  Basin,  with  a  Practical  Application,"  Amer. 
Jour.  Sci.,  iii.,  XXVII.,  49.  I.  C.  Russell,  "Geology  and  History  of  Lake 
Lahontan,  a  Quaternary  Lake  of  Northwestern  Nevada,"  Monograph, 
XL,  U.  S.  Oeol.  Survey;  also.  Third  Ann.  Rep.  Dir.  U.  S.  Geol.  Sut-vey, 
195.     C.  D.  Wolcott,  "  Paleontology  of  the  Eureka  District," -Monogrrop/j 


338  KEMP'S  ORE  DEPOSITS. 

2.11.13.  Lincoln  County  is  in  the  southeastorh  corner,  and 
contains  a  number  of  small  mining  districts.  The  ores  are  in 
general  silver-lead  ores  in  limestone,  or  veins  with  sulphiiret 
ores  in  quartzite  and  granite.  Pioche  is  one  of  the  principal 
towns,  near  which  is  found  the  once  famous  and  now  reopened 
Raymond  &  Ely  mine.  A  strong  fissure  cuts  Cambrian 
quartzite  and  overlying  limestone,  where  the  latter  has  not  been 
eroded,  and  is  occupied  by  a  great  porphyry  dike.  Along  the 
contact  between  the  porphyry  and  the  wall  rock  the  chutes  of  ore 
have  been  found.  Mi.  Ernest  Wiltsee,  at  the  Montreal  meeting 
of  the  American  Institute  of  Mining  Engineers,  February,  1893, 
described  and  figured  the  Half  Moon  mine,  on  this  same  great 
fissure,  where  the  quartzite  still  retained  a  limestone  cap.  The 
ore-bearing  solutions,  on  reaching  a  shaly  streak  containing  a 
limestone  layer,  departed  from  the  fissure  and  followed  under 
the  limestone,  so  as  to  form  a  lateral  enlargement,  much  like 
those  described  and  figured  from  Newman  Hill,  Colorado,  under 
2.09.10.  The  Pahranagat  and  Tern  Pahute  districts,  still  fur- 
ther south,  have  had  some  prominence,  but  the  whole  region  is 
so  far  from  the  lines  of  transportation  that  the  conditions  are 
hard  ones.^ 

2.11.14.  Ney  County,  next  west,  has  an  important  mining 
center,  in  its  northern  portion,  around  the  town  of  Belmont. 
Quartzites  and  slates  rest  on  granites  in  the  order  named,  and 
in  them  are  veins  with  quartz  gangue  and  silver  chlorides, 
affording  very  rich  ores.     Southeast  of  Belmont  is  Tybo.^ 

2.11.15.  White  Pine  County  lies  to  the  northeast,  and  con- 
tains the  White  Pine  district.  The  principal  town  is  Hamilton, 
about  110  miles  south  of  Elko,  on  the  Central  Pacific.  The 
Humboldt  range  is  prolonged  southward  in  some  broken  hills, 
consisting  chiefly  of  folded  Devonian  limestone.  At  Hamilton 
these  are  bent  into  a  prominent  anticline,  and  this  has  a  strong 
fissure  crossing  the  axis.    The  geological  section  is  Devonian 

VIII.,  U.  S.  Geol.  Survey.  Gilbert,  Wheeler,  Lockwood,  and  others, 
' '  Eastern  Nevada  :  Notes  on  its  Economic  Geology, "  Wheeler's  Survey, 
Rep.  Prog.,  1869,  71,  72;  also  Vol.  III.  and  Supplement.  For  further  lit- 
erature, see  under  Example  36. 

»  E.  P.  Howell,  Wheeler's  Survey,  III.,  257.  G.  M.  Wheeler,  Report, 
Wheeler's  Survey,  1869,  p.  14. 

'  S.  F.  Emmons,  Survey  of  the  Fortieth  Parallel,  Vol.  III.,  p.  393.  G.  K. 
Gilbert,  "On  Belmont  and  Neighborhood,"  Wheeler's  Survey,  III.,  36. 


SILVER  AND  OOLW,  CONTINUED.  339 

limestone,  thin  calcareous  shale,  thin  siliceous  limestone,  ar- 
gillaceous shale,  probably  Carboniferous  sandstone,  and  Carbon- 
iferous limestone.  The  ore  bodies  occur,  according  to  Arnold 
Hague,  in  four  forms,  all  in  the  Devonian  limestone:  (1)  in 
fissures  crossing  the  anticlinal  axis ;  (2)  in  contact  deposits  be- 
tween the  limestones  and  shales;  (3)  in  beds  or  chambers  in 
the  limestone  parallel  to  the  stratification;  (4)  in  irregular 
vertical  and  oblique  seams  across  the  bedding.  The  ore  is 
chiefly  chloride  of  silver  in  quartz  gangue.  It  is  thought  by 
Mr.  Hague  to  have  probably  come  up  through  the  main  cross 
fissure,  and,  meeting  the  impervious  shale,  to  have  spread 
through  the  limestone  in  this  way.* 

Egan  Canon  is  in  the  northern  part  of  the  county,  and 
shows  a  geological  section  of  granite,  quartzite,  and  slate  in  the 
order  named.  In  slates,  and  perhaps  extending  into  the  quart- 
zite, is  a  quartz  vein  five  to  eight  feet  wide,  carrying  gold  and 
silver  ores. 

Eureka  County  is  the  next  county  west  of  White  Pine.  The 
deposits  at  Eureka  have  already  been  described  under  "Lead- 
silver."  (Example  36.) 

2.11.16.  Lander  County  lies  next  west  to  Eureka.  The 
Toyabe  range  runs  through  it  from  north  to  south,  and  in  its 
southern  portion,  in  Nej^  County,  contains  the  Belmont  depos- 
its. (See  above,  2.11.14.)  At  Austin,  which  is  80  or  90  miles 
south  of  the  Central  Pacific  Railroad,  now  connected  with-  it 
by  a  branch,  are  the  mines  of  the  Reese  River  district,  named 
from  the  principal  stream  near  by.  From  Mount  Prometheus, 
which  consists  of  biotite  granite  or  granitite,  and  which  is 
pierced  by  a  great  dike  of  rhyolite,  a  western  granite  spur  runs 
out,  known  as  Lander  Hill.  The  ore  bodies  are  in  this  hill, 
and  are  narrow  fissure  veins  with  a  general  northwest  and 
southeast  trend,  carrj^ing  rich  ruby  silver  ores,  with  gray  cop- 
per, galena,  and  blende,  in  a  quartz  gangue  with  associated 
rhodochrosite  and  calcite.  They  are  also  often  faulted.  At 
times  they  show  excellent  banded  structure.  Antimony  has 
recently  been  found  in  this  region.^     (See  under  "Antimony.") 

*  J.  E.  Clayton,  "The  geological  structure  and  mode  of  occurrence  of 
the  silver  ores  in  the  White  Pine  district,"  Cal.  Acad.  Set.,  IV., 89.  A: 
Hague,  Fortieth  Parallel  Survey,  Vol.  III.,  p.  409. 

*  S.  F.  Emmons.  Fortieth  Parallel  Survey,  Vol.  III.,  p.  349. 


340  KEMP'S  ORE  DEPOSITS. 

2.11.17.  Elko  County  lies  north  of  White  Pine  and  Eureka 
counties,  and  contains  the  Tuscarora  mining  district.  The 
deposits  are  high-grade  silver  ores  in  veins,  in  a  decomposed 
hornblende  andesite.^ 

Humboldt  County  is  the  middle  county  of  the  northern  tier, 
and  contains  a  number  of  mining  disrticts,  which  produce  both 
silver  and  gold  from  quartz  veins  in  the  Mesozoic  slate.  Small 
amounts  of  the  precious  metals  come  also  from  Washoe  County, 
in  the  northwest  corner  of  the  State. ^ 

Churchill  County  adjoins  Lander  on  the  west,  and  pos- 
sesses a  few  silver  mines. 

Esmeralda  County,  in  the  southwest,  has  a  considerable 
number  of  rich  silver  and  gold  mines,  which  produce  high- 
grade  ores  from  veins,  with  a  quartz  gangue  in  metamorphic 
rocks,  slates,  schists,  etc.     (See  also  under  **Nickel.") 

2.11.18.  Storey  and  Lyon  are  two  small  counties  in  the 
western  central  portion  of  the  State,  but  the  former  contains 
the  most  important  and  interesting  ore  deposit  in  Nevada,  if 
indeed  it  is  not  the  largest  and  richest  single  vein  yet  discov- 
ered. 

2.11.19.  Comstock  Lode.  A  great  fissure  vein,  four  miles 
long,  forked  into  two  branches  above,  along  a  line  of  faulting 
in  eruptive  rocks  of  the  Tertiary  age,  and  chiefly  andesites. 
In  the  central  part  of  the  vein  the  displacement  has  been  about 
3,000  feet,  shading  out,  however,  at  the  ends.  The  ores  are 
high-grade  silver  and  gold  ores  in  quartz,  and  occur  in  great 
bodies,  called  *' bonanzas,"  along  the  east  vein.  Over  $325,- 
000,000  in  gold  and  silver  has  been  extracted,  in  the  ratio  of 
two  of  the  former  to  three  of  the  latter.  The  vein  lies  on  the 
easterly  slope  of  a  northeasterly  spur  of  the  Sierras.  West  of 
it  is  Mount  Davidson.  Theoutcroppings  lie  on  the  flank  of  the 
latter,  about  6,500  feet  above  the  sea  and  1,500  below  the  sum- 
mit. The  general  strike  of  the  vein  is  east  of  south,  and  it  dips 
east. 

Views  regarding  the  geology  of  the  Comstock  have  changed 
in  the  course  of  years,  as  they  have  been  influenced  by  the 
successive  writings  of  Von  Richthofen,  King,  Church,  Becker, 
and  Hague  and  Iddings,  the  points  in  especial  controversy 
being  the  determinations  of  the  rock  species. 

*  G.  F.  Becker,  Tenth  Cormis,  Vol.  XIII.,  p.  34.  «  Ibid.,  p.  33. 


SILVER  AND  QuLD,  CONTINUED.  3il 

2.11.20.  It  may  be  remarked  that  the  whole  scheme  of  the 
classification  of  the  volcanic  (effusive)  rocks  rests  largely  on 
Von  Richthofen's  earlj^  studies,  and  that  perhaps  the  most  im- 
portant generalization  of  late  years  is  due  to  the  work  of 
Hague  and  Iddings  on  the  same.  Von  Richthofen  (1865)  de- 
scribed the  ore  body  as  filling  a  fissure  on  the  contact  of  a  so- 
called  syenite,  and  an  eruptive  rock  that  he  called  "propylite." 
The  ore  and  gangue  are  thought  to  have  been  brought  up  from 
below  by  solfataric  action,  in  which  fluorine,  chlorine,  and 

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Fia.  134. — Section  of  the  Comstock  Lode  on  the  line  of  the  Sut7'o  tunnel.    After 

O.  F.  Becker,  Monograph  III.,  U.  8.  Geol.  Survey.     The  colors 

of  the  original  are  here  indicated  by  line-work. 

sulphur  were  the  principal  dissolving  agents.  Clarence  King 
(1867-68,  published  in  1870)  brings  out  forcibly  the  fact  that  the 
foot-wall  of  the  vein  approximates  closely  the  natural  continua- 
tion of  Mount  Davidson, and  contends  that  the  vein  filled  a  fissure 
between  the  syenite  of  which  Mount  Davidson  consists,  and  the 
late  Tertiary  eruptive  rocks  poured  out  against  its  flanks. 
He  traced  the  geological  succession  of  these  and  explained  the 
filling  of  the  vein  by  solfataric  action,  attendant  on  a  thin  dike 
of  andesite,  which  forced  its  way  into  the  contact.     J.  A.  Church 


342  KEMP'S  ORE  DEPOSITS. 

(1877)  thought  that  the  dlorite  (called  sj^enite  above)  of  Mount 
Davidson  had  been  extruded  originally  in  thin,  horizontal 
sheets,  which  were  folded  in  east  and  west  folds.  This  was  to 
account  for  the  sheeting  of  the  rocks  of  the  lode  as  now  seen. 
On  the  diorite  was  poured  out  next  the  propylite,  likewise  in 
successive  horizontal  sheets.  Then  they  were  all  tilted  along 
north  and  south  axes,  and  eruptions  of  andesite  penetrated  be- 
tween their  sheets  in  very  large  amount.  Further  movements 
forced  the  convexities  of  the  first-formed  folds  against  the  an- 
desites,  and  crowded  their  substance  sidewise,  to  some  extent, 
into  the  synclinals.  This  movement  slightly  parted  the  beds, 
affording  watercourses  through  which  rose  siliceous  waters. 
These  dissolved  away  the  neighboring  beds,  leaving  extensive 
quartz  bodies  in  their  places.  They  also  removed  the  andesite 
caps.  No  ore  was  formed  as  yet.  Now  followed  great  tra- 
chyte eruptions  on  the  east,  which  loaded  the  hanging  wall  of 
the  lode  so  heavily  as  to  cause  a  downward  movement  of  it  on 
the  foot,  making  a  new  series  of  openings,  and  into  these 
poured  the  ore-bearing  solutions  which  brought  the  precious 
metals.  No  one  who  has  intelligently  followed  this  explana- 
tion will  doubt  that  Mr.  Church  has  shown  great  ingenuity, 
and  yet  it  is  natural  to  prefer  to  avoid  so  long  and  involved  an 
hypothesis,  if  a  simpler  course  will  lead  to  the  same  results. 
At  the  time  of  Mr,  Church's  visit  the  workings  were  becom- 
ing very  deep,  and  the  great  heat,  which  has  been  since  such 
an  obstacle,  was  manifesting  itself.  Flooded  drifts,  it  was 
thought,  had  been  observed  to  grow  hotter,  and  from  this  the 
hypothesis  of  kaolinization  was  conceived.  It  was  that  the 
kaolinization  of  the  feldspar  in  the  deeply  buried  rock  oc- 
casioned the  heat  of  the  lode. 

2.11.21.  G.  F.  Becker  (1879-82)  comments  on  the  exces- 
sive alteration  which  the  rocks  have  undergone,  as  it  figures 
largely  in  his  hypothesis  of  origin.  He  then  traces  the  results  of 
faulting,  and  shows  that  under  conditions  like  those  present  the 
surface  would  tend  to  assume  a  logarithmic  curve,  which  coin- 
cides surprisingly  well  with  the  present  outline  of  the  country. 
After  describing  the  lode  itself,  the  orfgin  of  its  metalliferous 
contents  is  traced  as  follows.  Waters  under  hydrostatic  pres- 
sure from  the  heights  to  the  west  are  supposed  to  have  perco- 
lated toward  the  lode,  passing  through  deeply  buried  regions 


SILVER  AND  GOLD,   CONTINUED.  343 

of  heat.  They  were  probably  diverted  from  rising  directly 
through  the  lode  by  an  impervious  clay  seam,  and  v/ere  thus 
forced  to  traverse  the  diabase  hanging,  relieving  it  in  pas- 
sage of  the  metals,  which  were  afterward  deposited  in  the 
higher  portions  of  the  lode.  The  metals  themselves  were 
probably  largely  derived  from  the  augite  of  the  rock.  Mr. 
Becker  had  as  an  associate  Dr.  Carl  Bar  us,  who  studied  the 
heat  phenomena  (especially  the  hypothesis  of  kaolinization)  and 
the  electrical  manifestations  of  the  lode.  The  result  of  Dr. 
Barus's  careful  experiments  threw  great  doubt  on  kaolinization 
as  a  source  of  heat. .  The  electrical  experiments  were  not  satis- 
factory. .  They  were  carried  on  also  at  Eureka,  Nev.,  but  no 
very  definite  results  were  reached. 

2.11.22.  The  correct  determination  of  the  eruptive  rocks 
neighboring  to  the  Comstock  has  been  of  great  importance,  not 
alone  because  of  their  scientific  interest,  but  as  bearing  on  the 
fact  as  to  whether  the  lode  itself  was  a  contact  fissure  between 
two  different  rocks,  or  whether  it  was  simply  a  fissure  vein.  It 
is  worthy  of  note  that  in  connection  with  it  Von  Richthofen  de- 
veloped one  of  the  first  important  attempts  to  classify  the  vol- 
canic rocks,  and  that  Hague  and  Iddings  have  finally  urged 
that  the  peculiar  crystalline  textures  of  all  eruptive  rocks  de- 
pend primarily  on  the  rate  of  cooling  and  pressure  (i.e.,  depth 
below  the  surface)  under  which  they  have  solidified,  destroying 
thus  the  time  element  in  classification.  This  is,  to  be  sure, 
an  old  idea,  but  it  gains  its  best  confirmation  from  the  Com- 
stock. Von  Richthofen,  in  his  report  to  the  Sutro  Tunnel 
Company,  and  in  his  later  memoir  on  "The  Natural  System  of 
the  Volcanic  Rocks"  {Cal.  Acad.  /Set.,  1867;  s^ho Zeitschri ft 
d.  d.  geol.  (re.seZ/.,  1868,  663),  distinguished  in  the  Washoe  dis- 
trict syenite,  metamorphic  rocks,  quartz-porphyry,  propylite, 
sanidine- trachyte,  and  very  subordinate  andesite.  Mr.  King 
referred  much  of  the  propylite  of  Von  Richthofen  to  andesite, 
but  retained  the  propylite  as  a  distinct  species,  although  re- 
marking the  close  affinities  of  the  two.  The  quartz-porphyry 
he  called  quartz-propylite.  In  other  respects  no  changes  are 
introduced.  Zirkel  {Fortieth  Parallel  Survey,  Vol.  VI.)  de- 
termined the  syenite  as  granular  diorite,  and  while  accepting 
hornblende-propylite  and  quartz-propylite  as  separate  species, 
called  the  greater  part  of  the  quartzose  rock  dacite.     He  intro- 


344  KEMP'S  ORE  DEPOSITS. 

duced  for  the  first  time  augite-aodesite,  rhyolite,  and  basalt. 
Mr.  Church  paid  less  atteDtion  to  lithology,  and  used  the  terms 
of  his  predecessors  somewhat  loosely.  Mr.  Becker  makes  the 
following  classifications :  granular  diorite,  porphyritic  diorite, 
micaceous  diorite-porphyry,  quartz-porphyry,  earlier  diabase, 
later  diabase, earlier  hornblende-andesite,  augite-andesite,  later 
hornblende-andesite,  and  basalt.  In  this  it  will  be  seen  that 
several  new  varieties  are  introduced,  but  the  main  mass  of 
Mount  Davidson  was  still  considered  diorite,  and  the  vein  was 
thought  to  lie  between  this  and  some  of  the  other  species  men- 
tioned, especially  diabase.  In  1885,  Arnold  Hague  and  J.  P. 
Iddings  completed  new  microscopal  studies  upon  the  materials 
collected  by  Mr.  Becker,  and  the  results  were  published  as 
Bulletin  17  of  the  United  States  Geological  Survey  (*'0n 
the  Development  of  Crystallization  in  the  Igneous  Rocks  of 
Washoe,"  etc.).  These  two  writers  had  had  more  to  do  with 
the  eruptive  rocks  of  the  Great  Basin  and  the  Pacific  slope  than 
any  other  geologists,  and  hence  brought  to  the  review  an  ex- 
ceptional experience.  Nowhere  else  in  the  world  are  such  ex- 
posures and  thorough  sections  afforded,  alike  in  depth  and  in 
horizontal  extent.  Thay  proved  that  the  diabase  and  augite- 
andesite  shade  into  each  other,  the  differences  in  crystallization 
being  due  to  depth ;  that  the  hornblende  of  the  so-called  diorite 
was  largely  secondary  from  original  augite,  being  derived  hy 
paramorphic  change  (uralitization),  and  that  the  diorite  was  a 
structural  variety  of  the  diabase;  that  the  porphyritic  diorites 
shade  into  the  earlier  hornblende-andesites,  and  are  structural 
varieties  of  them ;  that  the  mica-diorites  and  hornblende-ande- 
sites are  related  in  the  same  way;  that  the  assumed  pre- 
Tertiary  age  of  the  quartz-porphyry  was  unwarranted,  and 
that  it  was  partly  dacite  and  partly  rhyolite,  the  two  shading 
into  each  other;  that  the  younger  diabase,  so-called,  of  the  sub- 
surface dike,  was  identical  with  the  rock  elsewhere  occurring 
on  the  surface  and  called  basalt,  and  was  really  a  basalt,  owing 
to  its  holocrystalline  character  to  its  depth ;  and  finally — the 
most  important  conclusion  of  all  in  this  connection,  although 
the  other  conclusions  are  among  the  most  important  advances 
made  in  late  years — **that  the  Comstock  Lode  occupies  a  line 
of  faulting  in  rock  of  the  Tertiary  age,  and  cannot  be  con- 
sidered as  a  contact  vein  between  two  different  rock  masses.'* 


SILVER  AND  GOLD,  CONTINUED.  345 

The  crystalline  structure  of  the  Washoe  rocks  has  been  sub- 
sequently treated  by  Mr.  Becker.  ('*The  Washoe  Rocks,'* 
Bull,  Cal.  Acad.  Set.,  Vol.  II.,  p.  93,  January,  1887;  "Tex- 
ture of  Massive  Rocks,"  Amer.  Jour.  Set.,  ii.,  Vol.  XXXIII., 
p.  50,  1887.)  The  various  structures — granular,  porphyritic, 
and  glassy — are  referred  more  to  differences  in  composition  and 
fluidity  than  to  circumstances  of  solidification.^ 

*  G.  F.  Becker,  ' '  Geology  of  the  Comstock  Lode  and  the  Washoe  Dis- 
trict," Monograph  III.,  U.  S.  Geol.  Survey.  Rec.  See  also  Eng.andMin. 
Jour.,  March  1,  1884,  p.  163;  IL  Ann.  Rep.  Dir.  U.  S  Geol.  Survey.  Rec. 
J.  A.  Church,  The  Comstock  Lode:  Its  Formation  and  history.  New  York : 
John  Wiley  &  Sons.  Reviewed  in  Eng.  andMin.  Jour.,  February  21,  1880 
p.  397.  See  also  shorter  papers  in  the  Eng.  and  Min.  Jour. ,  December 
28,  1878,  p.  456;  July  19,  1879,  p.  35;  December  12,  1885,  p.  397;  January, 
23,  1886,  p.  52.  "On  the  Changes  in  the  Comstock  Vein,"  Eng.  and  Min. 
Jour.,  December  18,  1886,  p.  434;  "The  Discovery  of  the  Comstock  Lode," 
Ihid.,  December  5  and  19,  1891,  and  other  papers  in  1892  by  Dan  De  Quille. 
Hague  and  Iddings,  "On  the  Development  of  Crystallization  in  the  Ig- 
neous Rocks  of  Washoe,  Nevada,"  etc..  Bull.  17,  U.  S.  Geol  Survey.  See 
also  Bull.  6,  Cal.  Acad.  Sci.,  and  Eng.  and  Min.  Jour.,  December  11. 
1886,  p.  415.     Charles  Howard  Shinn,  "The  Story  of  the  Mine,"  Hist. 


CHAPTER  XII. 

THE  PACIFIC  SLOPE :  WASHINGTON,  OREGON,  AND  CALIFORNIA. 

WASHINGTON. 

2.12.01.  Geology. — Little  is  available  in  the  way  of  system- 
atic descriptions  of  the  geology  of  Washington,  and  an  attrac- 
tive field  remains  to  be  developed.  The  ranges  of  the  Rocky 
Mountains  extend  across  the  panhandle  of  Ids  ho  and  show  in 
northeastern  Washington,  affording  considerable  amounts  of 
ores.  They  are  prevailingly  granite  and  gneiss,  which  have 
escaped  being  covered  by  the  enormous  volcanic  outbreaks  of 
Tertiary  and  later  time.  West  of  the  granites  a  great  plateau 
country  of  somew£at  diversified  surface  is  met.  It  seems  to 
have  been  an  ancient  lake  basin,  but  is  now  covered  by  igneous 
rocks  and  deposits  of  volcanic  tuff.  Still  farther  west  the 
Cascade  chain  forms  the  central  divide  of  the  State.  The 
rocks  are  granites,  flanked  by  Paleozoic,  Mesozoic,  and  meta- 
morphic  strata,  much  like  the  Sierras  of  California.  They 
v^rere  upheaved  in  large  part  before  the  Cretaceous,  and  since 
then  other  movements  have  occurred.  There  are  vast  develop- 
ments of  igneous  rocks,  forming,  as  at  Mount  Rainier,  some  of 
the  highest  American  peaks.  West  of  the  Cascade  range  is  a 
great  valley  formerly  marking  a  drainage  system,  but  now 
covered  partly  by  glacial  drift  and  partly  by  the  waters  of 
Puget  Sound.  The  glacial  deposits  are  enormous,  and  render 
the  problem  of  working  out  the  geology  wery  difficult.  Some 
glaciers  remain  on  the  heights  even  to  the  present  day.  West 
of  the  Puget  Sound  Basin  is  the  northerly  extension  of  the 
Coast  range,  locally  called  the  Olympics,  and  largely  Creta- 
ceous and  Tertiary  strata.^ 

1  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  27.     G.  A.  Bethune,   First 
Ann.  Rep.  State  Geol.,  1891.     A.  Bowman,  "  Mining  Developments  on  the 


THE  PACIFIC  SLOPE.  347 

2.12.02.  Good  descriptions  of  the  ore  deposits  of  Washington 
are  greatly  needed.  The  First  Annual  Report  of  the  State 
Geologist  has  little  of  scientific  value,  and  the  other  accounts 
are  more  or  less  obsolete.  There  are  gold  placers  in  Yakima, 
Stevens,  and  Kittitas  counties,  largely  worked  by  Chinese. 
But  in  Okanogan,  Snohomish  and  Stevens  counties,  in  the 
northeast,  the  developments  of  deep  mining  for  silver  ores, 
although  recent,  are  considerable.  The  Monte  Cristo  veins 
afford  great  quantities  of  refractory  and  rather  low  grade  ores, 
from  very  prominent  veins.  The  chief  country  rock  is  granite, 
but  numerous  dikes  of  more  basic  varieties ,  are  present.  The 
veins  are  largely  in  raetamorphic  rocks  and  contain  the  usual 
sulphides  in  quartz  gangue.^ 

OREGON. 

2.12.03.  Geology. — Northeastern  and  northern  central 
Oregon  are  formed  by  a  prolongation  southward  of  the  igneous 
plateaus  of  Washington.  Slates  and  granite  appear  in  Baker 
County  on  the  east,  in  the  Blue  Mountains,  and  the  geology 
seems  to  resemble  the  Sierras.  All  southeastern  Oregon 
belongs  in  the  Great  Basin,  which  comes  north  from  Nevada, 
but  is  better  watered  than  the  southern  portion.  It  is  traversed 
by  several  subordinate  ranges  of  the  block-tilted  basin  type. 
Of  these  the  Stein  Mountains  are  the  most  prominent.  The 
general  surface  is  formed    by  Quaternary  lake    deposits  and 

Northwest  Pacific  Coast  and  their  wider  Bearing,"  Trans.  Amer.  Inst. 
Min.  Eng. ,  XV. ,  707.  J.  MacFarlane,  Oeol.  Railway  Guide,  second  edition, 
p.  262;  notes  by  Pumpelly,  Willis,  and  others.  Rec.  J.  S.  Newberry, 
"Geology  and  Botany  of  the  Northern  Pacific  Railroad,"  Trans.  N.  Y. 
Acad.  Sci.,  III.,  1884,  p.  253.  C.  A.  White,  "  Puget  Group  of  Washing- 
ton," ^mer.  Jour.  Sci.,  iii.,  XXXVI.,  443.  B.  Willis,  "Our  Grandest 
Mountain  and  Deepest  Forest,"  School  of  Mines  Quarterly,  VIII.,  152. 
' '  Report  on  the  Coal  Fields  of  Washington  Territory, "  Tenth  Census,  Vol. 
XV.,  p.  759.  "  Some  Coal  Fields  of  Puget  Sound,"  XVIIL  Ann.  Rep.  Dir. 
U.  S.  Geol.  Survey,  Part  III.,  393.  "  Changes  of  River  Courses  in  Wash- 
ington Territory  due  to  Glaciation,"  Bull.  JfO,  U.  S.  Geol.  Survey.  "Drift 
Phenomena  of  Puget  Sound,"  Bull.  Geol.  Soc.  Amer.,  IX.,  III.,  1898. 

^  G.  A.  Bethune,  First  Ann.  Rep.  State  Geol,  1S91.  C.  N.  Fenner, 
"The  Monte  Cristo  District,  Snohomish  County,"  School  of  Mines  Quar- 
terly, November,  1892.  "The  Mines  of  Kittitas  County,"  Eng.  and  Min. 
Jour.,  December  24,  1892,  p.  608.  F.  L.  Nason,  "The  Auriferous  Gravels 
of  the  Upper  Columbia  River,"  E7ig.  and  Min.  Jour.,  March  21,  1896. 


348  KEMP'S  ORE  DEPOSITS. 

great  outbreaks  of  igneous  rocks.  West  of  the  basin  and  the 
plateau  the  Cascade  range  traverses  the  State,  and  is  cut  by  the 
Columbia  River  on  the  north  and  the  Klamath  on  the  south. 
The  range  consists  of  granite  and  metamorphic  rocks,  etc.,  the 
latter  chiefly  Mesozoic.  In  northern  Oregon  a  broad  valley 
intervenes  between  the  Cascade  and  the  Coast  ranges,  but  in 
the  southern  part  the  two  ranges  run  together,  and  their  dis- 
tinction has  been  only  partly  worked  out.  (See  Bull.  S3,  V. 
S.  Geol.  Survey. )  In  the  Coast  range  Cretaceous  and  Tertiary 
strata  predominate.^ 

2.12.04.  Oregon  is  an  important  producer  of  gold  both  from 
placers  and  from  veins.  Baker  County,  on  the  east,  presents 
the  characteristic  placers  and  gold  quartz  of  the  California 
Sierras,  and  is  the  most  productive  section  of  the  State.  Grant 
and  Josephine  counties  also  have  placers,  and  smaller  amounts 
come  from  a  few  others.  In  the  extreme  southeast,  near  the 
California  line,  is  Curry  County,  containing : 

2.12.05.  Example  44a.  Port  Orford.  Auriferous  beach 
sands  at  the  foot  of  gravel  clifiPs,  and  shifting  with  the  winds 
and  tides.  At  Port  Orford  the  ocean  has  access  to  great  sea 
cliffs  of  gravel  which  it  breaks  down  by  the  force  of  the  waves. 
A  sorting  action  ensues,  performed  by  the  undertow  and  the 
littoral  current.  The  heavier  gold  dust  is  concentrated  and  is 
gathered  up  by  the  miners  at  low  tide.  Some  submarine  work 
has  also  been  attempted.     The  product  is  not  great,  and  the 

^'  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  37.  T.  Condon,  "On  Some 
Points  Connected  with  the  Igneous  Eruptions  along  the  Cascade  Mountains 
of  Oregon,"  ^mer.  J oitr,  Sci.,  iii.,  XVIII.,  406.  J.  S.  Diller,  "Notes  on 
the  Geology  of  Northern  California,"  Bull.  33,  U.  S.  Geol.  Survey.  "A 
Geological  Reconnaissance  in  Northwestern  Oregon,"  XVII.  Ann.  Rep.  U. 
S.  Geol.  Survey,  Part  I.,  447,  with  notes  on  the  Economic  Geology  J.  C. 
Fremont,  "Observations  on  the  Rocky  Mountains  and  Oregon,"  xlmer. 
Jour.  Sci.,  ii..  III..  193.  George  Gibbs,  "Notes  on  the  Geology  of  the 
Country  East  of  the  Cascade  Mountains,  Oregon,"  Amer.  Jour.  Sci.,  ii., 
XX.,  375.  J.  Leconte,  "  On  the  Great  Lava  Flood  of  the  West  and  on  the 
Structure  and  Age  of  the  Cascade  Mountains,"  Amer.  Jour.  Sci.,  iii., VIII., 
167,  359.  C.  King,  Fortieth  Parallel  Survey,  Vol.  I.  J.  MacFarlane,  Geol. 
Railway  Guide,  p.  316.  J.  S.  Newberry,  Pacific  R.  R.  Reports,  Vol.  VI., 
pp.  1-73.  I.  C.  Russell,  "A  Geological  Reconnaissance  in  Southern  Ore- 
gon," TV.  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey,  pp.  435-463.  G.  O.  Smith. 
"The  Rocks  of  Mt.  Rainier,"  Idem,  416.  "Glaciers  of  Mt.  Rainier," 
XVIIL  Ann.  Rep.  U.  S.  Geol  Survey,  II.,  349. 


THE  PACIFIC  SLOPE.  349 

deposit  is  chiefly  interesting  in  its  scientific  bearing.  It  runs 
along  into  California  as  well.  Auriferous  sands  occur  at 
Yakutat  Bay,  Alaska.^  The  gold  of  the  Potsdam  sandstones 
of  the  Black  Hills  has  been  explained  in  a  similar  way,  but 
later  observations  have  modified  the  hypothesis.  The  magnetite 
sands  which  were  referred  to  under  2.03.13  furnish  something 
of  a  parallel.^ 

CALIFORNIA. 

2. 12.06.  Geology. — The  topography  and  geology  of  northern 
California  have  been  but  recently  made  clear.  Diller  considers 
that  the  southern  end  of  the  Cascade  range  is  Mount  Shasta ; 
that  the  Sierras  proper  terminate  near  the  north  fork  of  the 
Feather  River,  but  the  line  is  continued  about  fifty  miles  far- 
ther north,  in  the  Lassens  Peak  volcanic  ridge,  and  that  all 
else  west  and  south  of  Mount  Shasta  belong  to  the  Coast  range. 
Central  California,  as  is  well  known,  has  the  Sierras  on  the 
east,  the  great  Sacramento  Valley  in  the  middle,  with  the 
Coast  range  on  the  west.  The  arid  regions  of  the  Great  Basin 
just  touch  the  northeastern  corner,  but  on  the  southern  extrem- 
ity they  swing  around  and  form  a  large  part  of  the  State.  The 
Great  Basin  portion  is  formed  by  Quaternary  lake  deposits. 
The  Sierras  consist  of  central  granite  and  gneiss,  with  great 
developments  of  slates  and  eruptives  on  their  flanks.  The 
excessive  metamorphism  has  largely  destroyed  the  fossils,  but 
enough  have  been  found  to  prove  that  while  in  large  part 
Jurassic  and  Carboniferous,  Triassic  and  Silurian  representa- 
tives are  also  present.  The  western  slopes  have  the  mantles 
of  gravel,  which  have  furnished  so  much  gold,  and  with  these  are 
large  outflows  of  basalt.     The  upheaval  of  the  Sierras  occurred 

»  J.  Stanley-Browne,  Nat.  Geogr.  Mag.,  Vol.  III.,  196-198,  1891. 

*  G.  F.  Becker.  Tenth  Census,  Vol.  XIII.,  p.  27,  general  account  of  Ore- 
gon. W.  P.  Blake,  "Gold  and  Platinum  from  Cape  Blanco  (Port  Or- 
f ord ),"  ^mer.  Jour.  Sci.,  ii.,  XVIII.,  156.  "Remarks  on  the  Extent  of 
the  Gold  Regions  of  California  and  Oregon,"  etc.,  Amer.  Jour.  Sci.,  ii., 
XX.,  72.  A.  W.  Chase,  "The  Auriferous  Gravel  Deposits  of  Gold  Bluffs, 
California,"  Cal.  Acad.  Sci.,  1874;  Amer.  Jour.  Sci.,  iii.,  VIII.,  367. 
"Dredging  for  Gold,"  Eng.  and  Min.  Jour.,  June  23,  1883,  p.  360.  B.  Sil- 
liman,  "Cherokee  Gold  Washings,"  ^mer.  Jour.  Sci.,  iii.,  VI.,  132.  W. 
P.  Watts.  'Sands  in  Santa  Cruz  County,  California," -Rep.  Cal.  State 
Mineralogist,  1890,  p.  622. 


350  KEMP'S  ORE  DEPOSITS. 

before  the  middle  Cretaceous  time.  The  Coast  range  con- 
tains large  areas  of  sandstones,  cherts,  and  lavas,  probably  of 
Jurassic  age,  as  well  as  Cretaceous  and  Tertiary  strata.  They 
were  upheaved  in  post- Miocene  time.  Great  outbreaks 
of  andesite  also  occurred,  and  later  basalts.  The  prin- 
cipal product  of  California  is  gold,  but  there  are  dis- 
tricts which  have  furnished  considerabie  silver,  and  which  are 
first  described  in  order  to  lead  up  to  gold.  The  copper  and 
iron  resources  have  already  been  mentioned,  and  the  mercury, 
antimony,  and  chromium  deposits  remain  for  description  after 
the  "precious  metals.^ 

*  G.  F.  Becker,  "Notes  on  the  Early  Cretaceous  of  California,"  Amer. 
Jmir.  Sci.,  iii.,  II.,  20J.  "  Antiquities  from  under  Tuolumne  Table  Moun- 
tain, California,"  Bull.  Geol.  Soc.  Amer.,  II.,  189.  "Cretaceous  Metamorphic 
Rocks  of  California,"  Amer.  Jour.  Set.,  iii.,  XXXI.,  348.  "  Structure  of  a 
Portion  of  the  Sierra  Nevada  of  California,"  Bull.  Geol.  Soc.  Amer.,  II.,  50. 
"Notes  on  the  Stratigraphy  of  California,"  Bull.  19,  U.  S.  Geol.  Survey. 
W.  P.  Blake,  "Notes  on  Calif  ornia, "  Amer.  Jour.  Sci.,  ii.,  XVIII.,  441.  W. 
H.  Brewer  epitomizes  Whitney's  report,  Amer.  Jour.  Sci.,ii.,  XLI.,  231 ;  also 
351.  J.  D.  Dana,  "Notes  on  Upper  California,"  Amer.  Jour.  Sci.,  ii.,  VII., 
376.  J.  S.  Diller,  "Geology  of  the  Lassen  Peak  District, "  Eighth  Ann.  Rep. 
Dir.  U.  S.  Geol.  Survey,  pp.  401,435.  "On  the  Cretaceous  Rocks  of  North- 
em  California,"  Amer.  Jour.  Sci.,  Hi.,  XL.,  476.  "On  the  Geology  of  North- 
em  California,"  Proc.  Phil.  Soc.  of  Wash.,  January  16,  1886;  Abstract, 
Amer.  Jour.  Sci.,  iii.,  XXXIII.,  152.  "Geology  of  the Taylorville Region, 
Plumas  County,"  Bull.  Geol.  Soc.  Amer.,  III.,  369.  G.  K.  Gilbert,  "The 
Recency  of  Certain  Volcanoes  of  the  Western  United  States, "  Amer.  Assoc. 
Adv.  Sci.,  XXIII.,  29.  A.  Hyatt,  "Jura  and  Trias  of  Taylorville,  Cali- 
fornia," BwZZ.  Geol.  Soc.  Amer.,  III.,  395.  William  Irelan,  State  Mineral- 
ogist, ^nn.  Rep.,  1886,  and  following,  especially  1890,  geology  by  counties. 
J.  Leconte,  ' '  Post-Tertiary  Elevation  of  the  Sierra  Nevadas,  shown  by  the 
River  Beds."  Amer.  Jour.  Sci.,  iii.,  XXXII.,  167.  "Old  River  Beds  of  Cal- 
ifornia," J6id.,  iii.,  XIX.,  190;  iii.,  XXXVIII.,  261.  "Extinct  Volcanoes 
about  Lake  Mono,  and  their  Relations  to  the  Glacial  Drift,"  Ibid.,  iii., 
XVIII. ,  35.  Jules  Marcou,  ' '  Report  on  the  Geology  of  a  Portion  of  South- 
ern California,"  Wheeler  s  Survey,  Ann.  Rep.,  1876,  App.,  p.  158.  J.  E. 
Mills,  "Stratigraphy  and  Succession  of  the  Rocks  of  the  Sierra  Nevada  of 
California,"  Bull.  Geol.  Soc.  Amer.,  III.,  413.  E.  Reyer,  Theoretische 
Geologic,  p.  537,  1888.  I.  C.  Russell,  "The  Quaternary  History  of  Mono 
Valley,  California,"  Eighth  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey,  pp.  267-400. 
H.  W.  Turner,  "The  Geology  of  Mount  Diablo,  with  the  Chemistry  of  the 
RocksbyW.  H.Melville,"  Bull.  Geol.  Soc  Amer.,  II.,  383.  "Further  Con- 
tributions to  the  Geology  of  the  Sierra  Nevada,"  XVIII.  Ann.  Rep.  Dir.  U. 
S.  Geol.  Survey,  Part  I.,  p.  521.  Rec.  "The  Granitic  Rocks  of  the  Sierra 
Nevada,"  Jour.  Geol,  VII.,  141.  Rec.  J.  A.  Veatch,  "Notes  on  a  Visit 
to  the  Mud  Volcanoes  of  the  Colorado  Desert  "  etc  ,  Amer.  Jour.  Sci..  ii.. 


Fig.  l^^.—View  of  Randsburg,  Calif.,  looking  southwest.     Schists  underlie 
the  town,  but  the  hills  are  eruptive.     From  a  photo- 
graph by  H.  A.  Titcomb,  E.  M. 


Fig.  \Ti.—The  Stevens  Hydraulic  placer  mine,  Auro  City,  Colorado. 
From  a  photograph. 


^.^iM^^^i^^gy^^ll^i^^l^^^^jd^j^^j^jj^i 

iHHi 

gjHllll^^^^^^^Hgra 

g<.^.g—  --        -.        .r   »   ~-»>..-><v^„     ■r.^^.-.^-l      > .»-*^H^^^^^^^H 

Fig.  138. — View  in  the  Malakoff  Hydraulic  placer  mine,  North  BloomjieldL, 
California.     From  a  photograph. 


Fig.  139. — View  in  the  Malakoff  Hydraulic  placer  mine,  North  Bloomfield, 
California.     From  a  photograph. 


THE  PACIFIC  SLOPE. 


351 


2.12.07.  Calico  District.  Deposits 
of  silver  chloride  in  fissure  veins,  and 
in  small  fractures  and  pockets  in  lipa- 
rites,  tuft's  and  sandstones,  probably  of 
the  Pliocene  series.  They  occur  in 
Southwestern  California,  in  that  portion 
of  the  State  belonging  rather  to  the 
Greatps^asin  than  to  the  Pacific  slope. 
An  immense  outbreak  of  liparite  has 
formed  a  seri^R  of  elevations,  and  the 
attendant  tuffs  are  extensively  devel- 
oped. The  ore  is  thought  by  Lindgren 
to  have  come  in  heated  solution  from 
below  and  to  have  filled  the  fissures  and 
overflowed,  forming  the  surface  de- 
posits in  the  tuffs.  (Cf.  Silver  Cliff, 
Colorado.) 

2.12.08.  Likewise  in  the  desert  re- 
gion, a  gold  camp  has  sprung  up  at 
Kandsburg,  in  Kern  County.  Mica 
schists  form  the  country  rock  of  a  series 
of  hills  that  rise  above  an  abandoned 

XXVI.,  288.  J.  D.  Whitney  and  others,  reports 
of  the  CaUfornia  Geological  Survey,  issued  at 
Cambridge,  Mass.  L.  G.  Yates,  "Notes  on  the 
Geology  and  Scenery  of  the  Islands  forming 
the  Southern  Line  of  the  Santa  Barbara  Chan 
nel,"  Amer.  Geol,  V.,  43.  The  United  States 
Geological  Survey  has  prepared  a  number  of 
folios  on  the  geology  of  the  gold  belt,  which 
are  invaluable  to  all  who  are  interested  in  the 
region.  Each  embraces  a  geological  descrip- 
tion and  maps,  which  severally  show  the  topo- 
graphy, geology,  and  mineral  resources.  The 
following  have  been  issued  and  can  be  ob- 
tained at  25  cents  each  by  addressing  the  Di- 
rector of  the  U.  S.  Geological  Survey,  Wash- 
ington, D.C.  (the  Nevada  City  Folio  is  50 
cents) :  Placerville,  Sacramento,  Jackson, 
Lassen  Peak,  Marysville,  Smartsville,  Nevada 
City,  Pyramid  Peak,  Downieville,  Truckee, 
Sonora  and  Big  Tree.  Others  are  in  preparation. 


I- 


^ 


;.v>': 


:::'.'<*::•'■ 


352  KE^fP'S  ORE  DEPOSITS. 

lake  basio.  The  schists  are  seamed  by  dikes  of  porphyritic 
ruck,  which  may  have  come  from  the  volcaoic  ceDter  of  Red 
MouDtain  or  from  other  volcanic  emiDences  not  far  away. 
The  rock  from  the  central  and  south  peaks  of  Red  Mountain, 
when  examined  in  thin  sections  from  specimens  kindly  sent 
the  writer  by  H.  A.  Titcomb,  E.M.,  proved  to  be  hornblende- 
andesite,  but  the  dikes  from  the  vicinity  of  the  mines  were 
too  decomposed  for  recognition.  The  gold  ores  occur  iuagjuartz 
veins,  which  usually  are  in  association  with  the  porphyry 
dikes,  the  country  rock  being  the  mica  schist.  The  region 
suffers  for  lack  of  water,  but  as  it  is  now  connected  by  rail 
with  the  Santa  Fe  system,  a  number  of  mines  and  mills 
are  in  successful  operation.  The  accompanying  photograph 
(Fig.  130)  illustrates  the  country.^  The  remoteness  of  other 
camps  militates  against  their  development. 

2.1*2.09.  On  the  eastern  border  of  California  and  lying  along 
the  ea^ern  slopes  of  the  Sierras  are  Inyo  and  Mono  counties, 
two  that  have  been  quite  serious  producers  of  silver  (with  sub- 
ordinate gold)  in  past  years.  Deserted  or  greatly  dwindled 
mining  camps  are  frequently  met  throughout  the  mountains. 
The  region  lies  within  the  confines  of  the  Great  Basin,  and  is 
somewhat  poorly  supplied  with  water.  In  Inyo  County,  gran- 
ite, schists  and  crystalline  limestone  are  very  prominent  in  the 
general  geolc^y,  and  the  ores  are  prevailingly  of  the  lead-silver 
variety,  and  in  limestone  walls.  The  Cerro  Gordo  and  Pana- 
mint    districts    were  heavy  producers    in  their  day."     Mono 

*  F.  M.  Endlich,  "Mining  in  the  Mohave  Desert  of  California,"  Eng.  and 
Min.  Jour..  August  29.  1896.  147.  H.  G.  Hanks.  -On  the  CaHco  Dis- 
trict." Fourth  Rep.  Cal  State  Mineralogist.  1884.  366.  Wm.  Irelan,  -  On  the 
Calico  District.  •  Eighth  Rep.  Cal.  State  Mineralogist.  1888.  490.  W.  Lind 
gren.  "The  Silver  Mines  of  Calico  District.  California,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XT..  717.  F.  K  Nason.  "The  Goler  Gold  Diggings.  '  Eng.  and 
Min.  Jour.,  March  9,  1895.  2*33.  W.  A.  Skidmore.  "On  Calico  District," 
Rep.  Director  of  the  Mint.  1884.  539.  Rec.  Other  Reports  of  the  Director 
of  the  Mint  and  Raj-mond's  earlier  reports  may  be  advantageously  con- 
sulted. In  the  Min.  and  Sei.  Press.  April  1.  1899.  will  be  found  a  sketch 
of  the  Randsburg  district  and  of  the  Yellow  Aster  Mine.  The  notes  in 
the  text  on  Randsburg  were  based  on  specimens  and  data  kindly  furnished 
by  the  v\-riter's  friend.  H.  A.  Titcomb. 

'  H.  DeGroot.  "Report  on  Inyo  County."  Tenth  Rep.  Cal.  State  Mineralo 
gist.  1890.  209.  W.  A.  Goodyear.  "Report  on  Inyo  County/'  Eighth  Rep. 
Cal.  State  Mineralogist.  1888,  324-309.     Rec.     H.    G.   Hanks,  "SUver  in 


THE  PACIFIC  SLOPE.  353 

County  lies  Dext  north  of  Inyo,  and  is  remarkable  for  the  vast  de- 
velopment of  volcanic  rocks  that  it  contains.  While  there  are 
not  a  few  mining  districts  in  the  county  of  no  inconsiderable 
moment,  details  of  which  will  be  found  in  the  references  cited 
below,  yet  the  pre-eminent  one  is  Bodie.  At  Bodie  a  quite 
complex  series  of  veins  cut  hornblende-andesite,  over  which,  on 
the  surface,  is  volcanic  breccia.  Various  other  eruptives  occur 
in  the  neighborhood.  The  faults  in  which  the  veins  are  found 
have  been  formed  at  several  different  periods,  but  the  tracing 
of  their  exact  relations  will  require  very  careful  work.  The 
gangue  is  chiefly  quartz,  through  which  are  distribjited  silver 
minerals  with  more  or  less  gold.^  Nearly  all  the  other  deep 
mines  for  the  precious  metals  in  California  yield  little  else  than 
gold,  and  although  a  few,  such  as  those  at  Ophir,  afford  con- 
siderable silver,  they  will  be  mentioned  with  the  distinctively 
gold-quartz  veins. 

2.12.10.  Example  44.  Auriferous  Gravels.  (1)  River 
gravels,  or  placers  in  the  beds  of  running  streams.  These  have 
been  often  referred  to  in  other  States,  but  the  type  is  placed  in 
California,  as  they  are  there  best  known.  They  were  the  first 
gravels  washed  in  1849,  and  although  substantially  exhausted 
by  1860,  were  very  productive.  Eastward  from  the  great 
Sacramento  Valley  the  surface  rises  with  a  quite  gentle  gradi- 
ent to  the  summit  of  the  Sierras.  The  country  consists  chiefly 
of  metamorphic  rocks,  which  have  yielded  a  very  few  well- 
determined  fossils  of  both  Carboniferous  and  Jurassic  ages; 
but  the  identity  of  the  strata  in  all  the  area  is  diflScult 
to  make  out,  because  where  the  fossils  were  originally  present 
they  are  almost  entirely  destroyed  by   metamorphism.     Down 


California,"  Fourth  Rep.  Cal.  State  Mineralogist,  1884,  361.  W.  A.  Skid- 
more,  "Gold  and  Silver  Mining  in  California,  Past,  Present  and  Future," 
Rep.  of  Director  of  the  Mint,  1884,  538. 

^  H.  DeGroot,  "  Report  on  Mono  County,"  Tenth  Rep.  Cal.  State  Mineralo- 
gist, 1890,  336.  H.  W.  Fairbanks,  "Mineral  Deposits  of  Eastern  Califor- 
nia," Amer.  Geol.,  March,  1896,  144.  "Notes  on  the  Geology  of  Eastern 
California,"  Idem,  February,  1896,  63;  describes  Mono  and  Inyo  Counties. 
C.  D.  Walcott,  "Lower  Cambrian  Rocks  in  Eastern  California,"  ^wer. 
Jour.  *Scl,  February,  1895,  141.  "The  Appalachian  Type  of  Folding  in 
the  White  Mountain  Range  of  Inyo  County,  California,"  Idem,  March, 
1895,  169.  H.  A.  Whiting,  "Report  on  Mono  County,"  Eighth  Rep.  Cal. 
State  Mineralogist, '^^2-^02.     "On  Bodie,"  382-402.     Rec. 


354  KEMP'S  ORE  DEPOSITS. 

the  slopes  of  the  range  the  modern  streams  have  flowed  and 
cut  deep  canons  in  which  gravels  have  gathered.  Out  in  the 
more  open  country  the  gravels  have  also  accumulated  and  have 
furnished  some  productive  bars.  The  gold  has  been  derived 
principally  from  the  quartz  veins  of  the  slates,  which  are  later 
described,  and  has  been  mechanically  concentrated  in  the 
streams.  Befone  coming  to  its  final  rest  it  may  have  lodged  in 
the  high  or  deep  gravels,  of  which  mention  will  next  be  made. 

It  is  accompanied  by  magnetite  as  a  general  thing,  by  zir- 
con, garnet,  and  rarely  by  other  heavy  metals,  such  as  plati- 
num and  iridosmine.  The  greatest  amount  is  usually  near  the 
bedrock,  and  when  this  is  at  all  porous  the  gold  may  work 
into  it  to  a  small  distance  from  the  top.  The  gold  is  usually  in 
flattened  pellets  of  all  sizes,  from  the  finest  dust  to  nuggets  of 
considerable  weight,  which  show  evidence  of  being  water  worn. 
The  interesting  phenomena  connected  with  the  possible  circula- 
tion of  the  precious  metal  in  solution  through  the  gravels  are 
discussed  under  the  deep  gravels.  Important  deposits  of  the 
same  general  character  as  these  have  also  been  dug  over,  near 
Santa  Fe,  N.  M. ;  in  California  Gulch,  near  Leadville,  Colo. ; 
at  Fairplay,  Colo. ;  in  San  Miguel  County,  Colorado ;  in  the 
Sweetwater  district,  Wyoming;  near  Butte,  Mont.;  in  Last 
Chance  and  Prickly  Pear  gulches,  near  Helena,  Mont. ;  in  the 
Black  Hills;  in  southern  Idaho,  especially  along  the  Snake 
River;  and  at  various  points  in  Washington  and  Oregon. 
Placers  of  this  type  have  also  been  found  on  the  slopes  of  the 
Green  Mountains  and  in  the  Southern  States,  but  they  never 
have  proved  of  serious  importance. 

2.12.11.  (2)  High  or  Deep  Gravels.  With  the  exhaustion  of 
the  river  gravels  the  gold  seekers  of  California  were  driven  to 
prospect  on  the  higher  slopes,  where  auriferous  gravels  much 
less  accessible  had  long  been  noted.  Increasing  observation 
and  development  have  shown  that  these  are  the  relics  of  former 
and  very  extensive  drainage  systems,  which  were  more  or  less 
parallel  with  the  present  streams,  but  of  greater  volume. 
The  beds  lie  in  deep  gulches  in  the  slates,  and  are  capped  in 
most  cases  by  basaltic  lava  flows  or  by  consolidated  volcanic 
tuffs,  called  cement.  They  extend  some  250  miles  along  the 
Sierras  and  up  to  7000  feet  above  the  sea.  They  have  at  times 
great  thickness,  reaching  600  feet  at  Columbia  Hill,  but  drop 


THE  PACIFIC  SLOPE. 


355 


elsewhere  to  1  or  2  feet.  Thej-  vary  from  a  maximum  width  in 
workable  material  of  1,000  feet  to  a  minimum  of  150.  The 
inclosing  slates  on  the  sides  of  the  old  river  valley  are  called 
"the  rims,"  and  on  them  are  sometimes  found  other  gravels. 
In  some  districts  channels,  belonging  to  two  or  three  periods  of 
flow,  have  been  traced.  They  tend  to  follow  the  softer  strata, 
breaking  at  times  across  the  harder  rocks.  The  channel  filling 
consists  of  gravel,  sand,  and  clays,  volcanic  tuffs,  and  firm 
basalt.  With  these  are  great  quantities  of  silicified  trees,  and 
even  standing  trunks  project  through  some  beds.  The  gravel 
is  oftenest  formed  of  white  quartz  pebbles,  but  may  contain 
all  the  metamorphic  rocks  of  the  neighborhood,  and  even 
boulders  brought  from  a  great  distance.  The  gravel  at  times  is 
cemented  together  by  siliceous  and   calcareous  matter,  and  it 


Fig,  140. — Oeneralized  section  of  a  deep  graioel  bed,  with  technical  terms. 
After  R.  E.  Browne,  Rep.  Cal.  State  Mineralogist,  1890,  p.  437, 

then  requires  blasting;  but  loose  gravel  also  occurs.  The  clays 
are  locally  called  "pipe  clays,"  and  are  often  interbedded  with 
sand  layers.  They  are  blue  when  unoxidized,  giving  rise  to 
the  term  "blue  lead,"  but  red  oxidized  clays  are  not  infre- 
quent. The  clays  contain  many  leaf  impressions  of  species 
thought  by  Lesquereux  to  be  late  Tertiary.  (See  further  under 
2.12.13.)  The  gravels  also  contain  bones  of  extinct  vertebrates, 
and  have  afforded  some  authentic  human  remains  and  stone 
implements  of  good  workmanship.  The  volcanic  tuffs  have 
been  strong  factors  in  modifying  the  original  drainage  lines. 
They  have  flowed  into  the  ancient  valleys  in  a  state  of  mud  and 
have  then  consolidated. 

2.12.12.     The  richest  gravels  are  those  nearest  the  bed  rock. 


366 


KEMP'S  ORE  DEPOSITS. 


In  these  the  distribution  of  the  gold  is  governed  more  or  less 
by  the  character  of  the  ancient  channels.  It  favors  the  insides 
of  bends  and  the  tops  of  steeper  runs.  The  gradients  of  the  old 
channels  were  fairly  high,  often  running  100  to  200  feet  per 
mile.  Gold  has  also  been  found  by  assay  in  pyrite  that  has 
been  formed  in  the  gravels  since  their  deposition,  and  from 
this  it  is  evident  that  the  precious  metal  does  circulate  in  solu- 
tion with  sulphate  of  iron,  but  on  this  slender  foundation  some 
quite  unwarranted  chemical  hypotheses  for  the  origin  of  nug- 
gets have  been  based.  Substantially  all  the  gold  has  been  de- 
rived by  the  mechanical  degradation  of  the  quartz  veins  in  the 
slates  on  other  wall-rock. 

2.12.13.     The  depths  to  which  the  modern  streams  have  cut 


I|^G.  141. — Section  of  Forest  Hill  Divide,  Placer  County,  California,  to  illus- 
trate the  relations  of  old  and  modern  lines  of  drainage.     After 
R.  E.  Browne,  Rep.  Cal.  State  Mineralogist,  1890,  p.  4Ml. 

out  their  channels  below  the  old  drainage  lines  have  received 
considerable  attention.  Whitney  concluded  that  no  disturb- 
ance had  taken  place  since  the  old  gravels  were  laid  down,  but 
Le  Conte  has  inferred  that  there  has  been  a  tilting  or  elevation 
of  the  higher  parts  of  the  range,  all  moving  as  a  block.  Becker 
has  recently  described  in  the  high  portions  a  great  series  of  small 
north  and  south  faults  with  uniform  downthrow  on  the  western 
side  or  upthrow  on  the  eastern.  (See  paper  below,  cited  from 
Geological  Society  of  America.)  This  is  supposed  to  have  been 
of  varied  intensity  in  different  portions  and  to  have  been  limited 
to  the  atrip  just  west  of  the  summit.  It  is  attributed  to  the  Plio- 
cene and  is  thought  to  have  increased  the  gradient  of  the  streams 
where  the  present  deep  canons  occur,  but  to  have  had  no  effect 


THE  PACIFIC  SLOPE.  357 

near  the  plains,  where  the  oJd  and  new  channels  are  nearly  on 
the  same  level.  Later  work  has  oast  much  doubt  on  these  views. 
2.12.14.  After  the  formation  of  the  deep  gravels  and  after 
the  volcanic  flows,  glaciation  took  place  in  great  extent  over  the 
mountain  sides,  but  it  was  doubtless  later  in  time  than  the 
glacial  period  of  the  East.  Eeferences  to  the  similar  great  de- 
velopment of  the  ice  in  Washington  have  already  been  made. 
Many  hypotheses  were  early  advanced  to  explain  the  deep 
gravels.  They  have  been  referred  to  the  ocean,  to  ocean  cur- 
rents, and  to  glaciers;  but  it  is  now  well  established  that  they 
are  river  gravels,  formed  when  the  rainfall  was  probably  in 
excess  of  what  it  is  to-day,  and  when  the  attitude  of  the  land 
toward  the  ocean  probably  was  different.^ 

'  G.  F.  Becker,  'Notes  on  the  Stratigraphy  of  Calif arnia,"  Bull.  19,  U. 
S.  Geol.  Survey.  "Structure of  the  Sierra Nevadas, "  Geol.  Soc.  Amer.,  XL, 
43.  W.  P.  Blake,  "The  Various  Forms  in  which  Gold  Occurs,"  Rep.  Direc- 
tor of  the  Mint,  1884,  p.  573.  A.  J.  Bowie,  Jr.,  "Hydraulic  Mining  in  Cal- 
ifornia," Trans.  Amer.  Inst.  Min.  Eng.,  VI.,  27.  R.  E.  Browne,  "The  An- 
cient River  Beds  of  the  Forest  Hill  Divide,"  Rep.  Cal.  State  Mineralogist, 
1890,  p.  435.  Rec.  "California  Placer  Gold,"  Eng.  and  Min.  Jour.,  February 
2,  1895,  101.  T.  Egleston,  "Formation  of  Gold  Nuggets  and  Placer  De- 
posits," Trans.  Amer.  Inst.  Min.  Eng.,  IX.,  63.  "Working  Placer  Depos- 
its in  the  United  States,"  School  of  Mines  Quarterly,  VII.,  p.  101.  J.  H. 
Hammond,  "Auriferous  Gravels  of  California,"  Rep.  Director  of  the  Mint, 
1881,  p.  616.  Rec.  Rep.  Cal.  State  Mineralogist,  1889,  p.  105.  H.  G. 
Hanks,  "Placer  Gold,"  Rep.  Director  of  the  Mint,  1882,  p.  728.  H.  G. 
Hanks,  William  Irelan  and  J.  J.  Crawford,  Rep.  Cal.  State  Mineralogist, 
Annual.  T.  S.  Hunt,  'On  a  Recent  Formation  of  Quartz,  and  on  Silici- 
fication  in  California,"  Eng.  and  Min.  Jour.,  May  29,  1880,  369.  J.  Le- 
conte,  "The  Old  River  Beds  of  California,"  Amer.  Jour.  Sci.,  iii.,  XIX., 
80,  p.  176.  J.  J.  McGillivray,  ' '  The  Old  River  Beds  of  the  Sierra  Nevada  of 
California,"  Rep.  Director  of  the  Mint,  1881,  p.  630.  R.  I.  Murchison, 
' '  Siluria,"  etc. ;  contains  a  sketch  of  the  distribution  of  gold  over  the  t  i  th. 
F.  L.  Nason,  "The  Goler  Gold  Diggings,"  Eng.  and  Min.  Jour.,  Mc  .en  9, 
1895,  223.  J.  S.  Newberry,  "On  the  Genesis  and  Distribution  of  Gold," 
School  of  Mines  Quarterly,  Vol.  III. ;  Eng.  and  Min.  Jour.,  December  24 
and  31,  1881.  J.  A.  Phillips,  "Notes  on  the  Chemical  Geology  of  the 
California  Gold  Fields,"  Philos.  Mag.,  Vol.  XXXVI.,  p.  321;  Froc.  Roy. 
Soc,  XVI.,  294;  Amer.  Jour.  Sci.,  ii.,  XLVII.,  134.  F.  L.  Ransome,  "The 
Great  Valley  of  California:  A  Criticism  of  Isostasy,"  Bull.  Dept.  of  Geol, 
Univ.  of  Cal,  I.,  370-428,  1896.  B.  Silliman,  "On  the  Deep  Placers  of 
the  South  and  Middle  Yuba,  Nevada  County,  CaUfornia,"  Arner.  Jour. 
Sci.,  ii.,  XL.,  1.  J.  D.  Whitney,  "Auriferous  Gravels  of  the  Sierras," 
Cambridge,  1880.  "Climatic  Changes  in  Later  Geological  Times,"  Cam- 
bridge.    See  also  references  on  succeeding  pages  relating  to  California. 


358  KEMP'S  ORE  DEPOSITS. 

2.12.15.  The  U.  S.  Geological  Survey  has  been  directiog 
its  attention  in  recent  years  to  the  geology  of  the  gold  belt  in 
the  Sierras  in  connection  with  the  issue  of  atlas  sheets,  based 
on  topographic  and  geologic  surveys.  Several  of  these  are 
practically  complete,  and  they  and  the  auxiliary  papers  which 
have  resulted  from  the  work  have  served  to  throw  a  flood  of 
light  upon  the  obscure  problems  of  the  geology  of  the  Sierras. 
At  the  same  time,  as  cited  under  subsequent  paragraphs,  other 
local  workers  have  been  active.  The  geological  relations  of 
the  gravels  as  well  as  the  solid  strata  have  been  made  clear  in 
greater  detail  than  ever  befoi  e.  Waldemar  Lindgren  has  dis- 
cussed the  geological  history  of  the  American  and  Yuba  rivers 
in  his  valuable  paper  entitled,  '*Two  Neocene  Rivers  of  Cali- 
fornia" {Bull.  Geol.  Soc.  of  America,  IV.,  257,  1893.)  The 
conclusion  is  that  the  old  divide  in  general  coincided  with  the 
present  one,  but  that  the  slope  of  the  Sierra  has  been  consider- 
ably increased  since  the  time  when  the  Neocene  {i.e.,  Miocene 
and  Pliocene)  ante- volcanic  rivers  flowed  over  its  surface.  "It 
finally  appears  probable  .  .  .  that  the  surface  of  the  Sierra 
Nevada  has  been  deformed  during  this  uplift,  and  that  the 
most  noticeable  deformation  has  been  caused  by  a  subsidence  of 
the  portion  adjoining  the  great  valley,  relatively  to  the  middle 
part  of  the  range. ' '  A  careful  review  of  the  age  of  the  aurifer- 
ous gravels  in  general  by  Lindgren,  and  of  the  fossil  plants 
from  Independence  Hill,  by  Knowlton,  has  led  to  the  conclu- 
sion that  the  deep  gravels,  which  themselves  lack  fossils,  date, 
in  instances,  probably  as  far  back  as  the  Eocene,  but  not  earlier. 
Some  bench  gravels  certainly  were  strongly  developed  in  the 
Miocene  and  gravels  of  one  sort  or  another  have  been  formed 
from  that  time  to  the  present.^ 

Lindgren  has  even  brought  to  light  the  existence  of  an  aurif- 
erous conglomerate  in  the  upturned  Mariposa  beds  of  Jurassic 
age,  near  Mine  Hill,  Calaveras  County.  The  crushed  con- 
glomerate gave  good  colors,  bat  no  black  sand,  from  which  it 
was  inferred  with  great  reason  that  the  gold  came  from  veins 
already  existing  in  pre- Jurassic  time  in  the  earlier  strata  and 
before  the  intrusion  of  the  basic  igneous  rocks  of  the  region.^ 

^  W.  Lindgren,  "  Age  of  the  Auriferous  Gravels  of  the  Sierra  Nevada," 
with  a  Report  on  the  Flora  of  Independence  Hill,  by  F.  H.  Knowlton, 
Jour.  Oeql,  IV.,  881,  1896. 

'  W.  Lindgren,  "  Auriferous  Conglomerate  of  Jurassic  Age  in  the  Sierra 
Nevada,"  Amer.  Jour.  Sci.,  October,  1894,  275. 


THE  PAClPiG  SLOPE.  359 

H.  W.  Fairbanks  has  cod tro verted  the  above  interpretation 
and  regards  the  presence  of  the  gold  as  due  to  later  mineraliza- 
tion.^ 

Fairbanks  also  takes  issue  with  the  interpretation  by  R.  L. 
Dunn  of  an  auriferous  conglomerate  in  the  Klamath  Moun- 
tains, as  a  river  gravel  of  pre-Chico  age,  regarding  it  rather  as 
shore  conglomerate  in  the  Chico  itself.^ 

J.  S.  Diller  has  discussed  the  early  physiography  but  for 
a  wider  range  of  country  than  any  of  the  papers  hitherto 
<5ited.^  Mr.  Diller  shows  that  the  western  side  of  the  present 
Sierras  formed  in  the  Eocene  or  Tejon  times  a  gently -sloping 
base-level  of  erosion,  with  quiet  streams  and  extensive  super- 
ficial deposits  of  a  residual  character.  The  Sierras  were  from 
4,000  to  7,000  feet  below  their  present  altitude.  With  the 
Miocene  came  a  period  of  upheaval,  of  increased  gradients  and 
rapid  denudation  of  the  soft  surface  materials.  The  old  aurif- 
erous gravels  were  thus  formed  in  the  stream  channels  while 
the  lighter  materials  were  transported  out  to  sea.  The  course 
of  development  is  graphically  traced  out  by  Diller  in  ac- 
cordance with  our  modern  knowledge  of  stream -erosion  and 
transportation.  For  southern  California,  A.  C.  Lawson  has 
described  a  somewhat  similar  development  in  later  geolog- 
ical time,*  but  as  the  region  is  not  one  of  auriferous  gravels, 
it  is  only  cited  here  as  of  interesting  correlative  character.  H. 
W.  Turner  has  lately  reviewed  the  whole  stratigraphy  of  the 
region  south  of  the  fortieth  parallel,  has  correlated  the  new 
formational  names  adopted  in  the  survey  atlas  sheets,  has 
added  many  valuable  notes  on  the  petrography  of  the  igneous 
rocks,  and  has  outlined  the  stratigraphical  relations  of  the 
gravels.^  Mr.  Turner  distinguishes  two  series  of  Neocene 
river  gravels     (p.   241).       (1)    The   older    gravels    composed 

^  H.  W.  Fairbanks,  "Auriferous  Conglomerate  in  California,"  Eng.  and 
Min.  Jour.,  April  27,  1895,  389. 

'  R.  L.  Dunn,  Twelfth  Ann.  Rep.  Cal.  State  Mineralogist,  1894,  459. 

^  J.  S.  Diller,  ' '  Revolution  in  the  Topography  of  the  Pacific  Coast  since 
the  Auriferous  Gravel  Period,"  Jour.  Geol.,  II.,  32,  1894. 

*  A.  C.  Lawson,  "The  Post-Pliocene  Diastrophism  of  the  Coast  of 
Southern  California,"  Bull.  Dept.  of  Geol.,  Univ.  of  Cal,  I.,  115,  Decem- 
ber. 1893. 

^  H.  W.  Turner,  "Geological  Notes  on  the  SieiTa Nevada,"  Amer.  OeoL, 
XIII..  pp.  228,  297,  1894. 


360  KEMP'S  CRE  DEPOSITS. 

chiefly  of  white  quartz  pebbles  and  frequently  capped  by  rhyo- 
litic  flows.  These  may  be  characterized  in  a  broad  way  as  the 
gravels  formed  before  the  volcanic  period.  (2)  A  later  series, 
containing  volcanic  pebbles  chiefly  of  andesite  and  later  in  age 
than  the  rhyolitic  flows.  These  may  be  called  the  gravels  of 
the  volcanic  period.  Such  gravels  are  often  capped  by  andesite- 
tuffs.  Included  fossil  leaves  indicate  that  the  older  gravels  are 
Miocene  or  Eocene;  the  later,  Pliocene.  The  Pliocene  river 
gravels  merge  into  shore  gravels  of  the  same  age  in  Amador  and 
Calaveras  counties.  The  pebbles  in  the  shore  gravels  are  quartz- 
ite,  mica-schist,  quartz-porphyrite,  granitoid  rocks,  andesite, 
and  rhyolite,  the  last  named  being  at  times  very  abundant  and 
characteristic.  They  appear  to  have  been  deposited  along  the 
shores  of  the  great  gulf  which  filled  the  central  valley  of  Cali- 
fornia in  these  times.  They  now  range  as  a  general  thing  500 
to  700  feet  above  the  sea.  Later  than  the  Pliocene  gravels  are 
the  Pleistocene,  both  shore  and  river  deposits.  The  former 
occur  in  the  depressions  between  the  Neocene  and  older  hills 
and  at  a  lower  altitude,  by  one  to  several  hundred  feet.  They 
seem  to  consist  of  the  harder  pebbles  of  the  Pliocene  gravels, 
the  softer  ones  having  been  destroyed  by  abrasion.  The  Pleis- 
tocene river  gravels  lie  usually  less  than  100  feet  above  the 
present  streams,  and  also  in  remnants  of  the  channels  left  be- 
hind by  old  changes  of  course.  They  and  the  shore  deposits  of 
this  time  are  often  highly  auriferous.  Several  lake- bottoms  of 
this  period  have  been  recognized  where,  for  some  reason,  such 
as  the  damming  of  a  stream  by  a  volcanic  flow,  or  a  probable 
mountain  upheaval,  the  waters  were  set  back.  These  lakes 
have  left  benches  which  mark  their  old  shore  lines.  Finally, 
we  have  the  recent  stream  gravels  and  alluvium.  These  papers 
show  that  the  geological  relations  are  more  complex  than  was 
earlier  known,  but  in  their  practical  bearings  the  gravels  can 
perhaps  hardly  be  better  grouped  than  into  the  River  gravels 
or  placers,  in  the  beds  of  running  streams,  and  the  High  or 
Deep  gravels,  according  to  the  old  nomenclature. 

2.12.16.  In  resume  of  the  above  review  it  should  be  first 
appreciated  that  stream  gravels  are  the  least  favorable  of  all 
sediments  to  the  preservation  of  organic  remains.  Not  only 
are  few  animals  with  hard  parts  resident  of  swiftly  flowing 
currents,  but  such  shells  or  bones  as  might  reach  them  would 


THE  PACIFIC  SLOPE.  361 

be  liable  to  destruction  from  the  trituration  of  the  boulders. 
The  stratigraphical  relations  of  the  gravels  must  therefore  be 
worked  out  in  great  part,  by  other  forms  of  evidence.  It 
should  also  be  appreciated  that  the  old  channel-fillings  remain 
to  us  to-day  only  as  fragments  of  their  former  extent,  and  that 
they  are  largely  buried  under  lava  flows  and  tuffs.  The 
gravels  therefore  appear  in  narrow  outcrops  and  set  up  narrow 
valleys,  which  are  cutoff  from  their  neighbors,  north  and  south 
by  high  divides.  While  they  were  being  deposited,  moreover, 
in  past  geological  time,  more  extensive  contemporaneous  forma- 
tions were  being  laid  down  in  the  then  submerged  valley  of 
California,  and  with  the  latter  it  is  important  to  correlate  them. 
The  kinds  of  evidence  that  are  available  are  the  following :  The 
lithological  character  of  the  pebbles ;  the  relations  of  the  non- 
fossiliferous  gravels  to  others  in  whose  interbedded  clays  or 
tuffs,  fossil  plants  occur;  the  physiographic  conditions  under 
which  the  gravels  were  laid  down,  and  which  must  have  been 
uniform  over  a  great  part  of  the  State  and  have  left  correlative 
records,  if  they  can  be  found ;  and  finally  the  relations  of  the 
gravels  to  the  volcanic  outbreaks,  whose  lithological  succession 
may  be  worked  out. 

In  the  following  tabular  statement  the  endeavor  has  been 
made  to  utilize  the  classification  of  the  gravels  into  periods, 
which  was  prepared  by  Ross  E.  Browne  (10th  Ann.  Rep.  Calif: 
State  Mineralogist,  437)  and  add  thereto  other  determinations 
by  the  geologists  of  the  U.  S.  Survey,  or  by  California  geologists. 
Jurassic.  Auriferous    gravel,    now   a    con- 

glomerate.^ 
Cretaceous.  Pre-Chico  auriferous  river  gravel 

in  the    Klamath    Valley,    Siskiyou 
County.*'        (They     may    be   beach 
gravels  of  the  Chico  itself.)^ 
Eocene.  Auriferous  gravels  doubtful. 

Miocene.  Deep  gravels  with  quartz   pebbles 

of  Browne's  First  Period,^  which  was 

'  W.  Lindgren,  "An  Auriferous  Conglomerate  of  Jurassic  Age  from  the 
Sierra  Nevada, "  Amer.  Jour.  Sci. ,  October,  1894,  275 ;  see  also  H.  W.  Fair- 
banks, Eng.  and  Min.  Jour.,  April  27,  1895,  389. 

'  R.  L.  Dunn,  "Auriferous  Conglomerate  in  California,"  Twelfth  Arm. 
Rep.  Cal.  State  Mineralogist,  1894,  459;  see  also  H.  W.  Fairbanks  as 
under  preceding  reference. 

^  Ross  E.  Browne,  "The  Ancient  River  Beds  of  the  Forest  Hill  Divide. '^ 
Tenth  Ann.  Rep.  Cal.  State  Mineralogist,  1^90,  4:3 7-440. 


36a 


KEMP'S  ORE  DEPOSITS. 


closed  by  Pliocene  andesite  erup- 
tions.  The  chief  auriferous  gravels 
belong  in  this  period.  Bench  gravels. 
Some  rhyolite  eruptions  occurred 
during  it.^  (Turner's  **  Intermedi- 
ate Period,"^  pebbles  of  pre-Creta- 
'  ^  ceous  sedimentary  and  igneous  rocks; 

presumably     later     than    the     first 
period,  but  of  uncertain    taxonomic 
relations  with  the  second  period.)^ 
Miocene  Second  Period  of  Browne*  gravels 

Pliocene.  formed  in  shifting  channels  during 

or  between  successive  volcanic  erup- 
tions and  mud  flows,  both  of  andesitic 
nature.     Pebbles  mostly  volcanic. 
Pliocene  to  Third    Period  of  Browne,*  dating 

Present.  from  last  important  lava  and  mud- 

flow;  beginning   and  completion  of 
present      stream      valleys.       River 
gravels. 
2.12.17.     Example  45.     Gold  Quartz  Veins.     Veins  of  gold- 
bearing  quartz,  often  described  as  segregated  veins,  in  slates  or 
metamorphosed  igneous  rocks,  and  more  or  less  parallel  with 
the  schistosity.     Less  commonly  the  walls  are  massive,  igneous 
rocks.      The    quartz    contains    auriferous   pyrite,    free  gold, 
arsenopyrite,   chalcopyrite,   tetrahedrite,    galena,  and  blende, 
but  pyrites  is  far  the  most  abundant.     Tellurides  have  been 
occasionally  detected  in  small  amounts.*    The  veins  approxi- 
mate at  times  a  lenticular  shape,  which  is  less  marked  in  Cal- 
ifornia than  in  some  other  regions,  and  which  shows  analogies 
of  shape  with  pyrites  lenses  (Example  16)  and  magnetite  lenses 

*  H.  W.  Turner,  "Auriferous  Gravels  of  the  Sierra  Nevada,"  Amer. 
Geol,  June,  1895,  372. 

^  Lindgren  and  Knowlton,  "Age  of  the  Auriferous  Gravels  of  the  Sierra 
Nevada,"  Jour.  Geol,  IV.,  881,  1896;  see  especially  table,  p.  906. 

^  Ross  E.  Browne,  "The  Ancient  lliver  Beds  of  the  Forest  Hill  Divide," 
Tenth  Ann.  Rep.  Cal.  State  Mineralogist,  1890,  437-440. 

Each  of  the  above  papers  has  important  complementary  relations  to  the 
others. 

*  For  a  review  and  bibliography  of  the  Tellurides,  see  J.  F.  Kemp,  The 
Mineral  Industry,  Vol.  VI. ,  p.  295. 


THE  PACIFIC  SLOPE.  363 

'(Example  12).  In  such  cases  the  fissure-vein  character  is 
somewhat  obscure.  In  California  the  veins  occupy  undoubted 
fissures  in  the  slates.  The  largest  and  best  known  is  the  so- 
called  Mother  Lode,  which  is  a  lineal  succession  of  innumerable 
larger  and  smaller  quartz  veins  that  run  parallel  with  the  strike, 
and  rarely  cut  the  steep  dip  of  the  slates  at  an  angle  of  10°.  It 
was  doubtless  formed  by  faulting  in  steeply  dipping  strata.  The 
wall  rocks  of  the  California  veins  embrace  many  types  of  igneous 
rocks,  as  well  as  sedimentary  slates,  for  all  these  enter  into  the 
western'  slopes  of  the  Sierras.  The  frequent  serpentine  is  prob- 
ably a  metamorphosed  igneous  rock,  while  the  diabase  and 
diorite  form  great  dikes.  Considerable  calcite,  dolomite,  and 
ankerite  occur  with  the  quartz,  and  very  often  it  is  penetrated 
by  seams  of  a  green,  chloritic  silicate,  which  was  provisionally 
called  mariposite,  but  which  has  been  shown  by  Turner  to  be  a 
potassium  mica,  colored  green  by  chromium.  The  quartz 
veins  vary  somewhat  in  appearance,  being  at  times  milk 
white  and  massive  (locally  called  "hungry,"  from 
its  general  barrenness),  at  times  greasy  and  darker, 
and  again  manifesting  other  differences,  which  are 
difficult  to  describe,  although  more  or  less  evident  in  speci- 
mens. The  richer  quartz  in  many  mines  is  somewhat  banded, 
and  is  called  ribbon  quartz.  The  quartz  has  been  studied  in 
thin  sections,  especially  in  rich  specimens,  by  W.  M.  Courtis, 
who  shows  that  fluid  or  gaseous  inclusions  of  what  is  probably 
carbonic  acid  are  abundant.  In  rich  specimens  the  cavities  tend 
to  be  more  numerous  than  in  poor,  but  more  data  are  needed  to 
form  the  basis  of  any  reliable  deductions.  Some  quartz  shows 
evidence  of  dynamic  disturbances.  The  walls  of  the  veins  are 
themselves  at  times  impregnated  with  the  precious  metal  and 
the  attendant  sulphides.  The  rich  portions  of  the  veins  occur 
in  chutes  which  run  diagonally  down  on  the  dip. 

2.12.18.  The  great  Mother  Lode  is  the  largest  group  of 
veins  in  California.  It  extends  112  miles  in  a  general  north- 
west direction.  Beginning  in  Mariposa  County,  in  the  south, 
it  crosses  Tuolumne,  Calaveras,  Amador,  and  El  Dorado  coun- 
ties in  succession.  It  is  not  strictly  continuous  nor  is  it  one 
single  lode,  but  rather  a  succession  of  related  ones,  which 
branch,  pinch  out,  run  off  in  stringers,  and  are  thus  complex 
in  their  general  grouping.     Over  500  patented  locations  have 


364 


KEMP'S  ORE  DEPOSITS. 


been  made  od  it.  Whitney  suggested  that  it  may  have  origi- 
nated from  the  silicification  of  beds  of  dolomite,  but  others  re- 
gard it,  with  greater  reason,  as  a  great  series  of  veins  along  a 

Surface 


Surface 


100        200        300        400        500  Ft. 


Figs.  143  and  144. — Ore  shoots  of  Nevada  City  and  Grass  Valley  mines,  Col. 

After  W.  Lindgren,  XVII.  Aim.  Rep.  U.  8.  Oeol.  Sm^ey, 

Part  II.,  Plate  XVIII.,  slightly  reduced. 

fissured  strip.  The  veins  are  often  left  in  strong  relief  by  the 
erosion  of  the  wall  rock,  and  thus  are  called  ledges,  or  reefs. 
Some  discussion  has  arisen  over  the  condition  of  the  gold    in 


THE  PACIFIC  SLOPE. 


365 


the  pyrite,  but  in  most  cases  it  is  the  native  metal  mechanically 
mixed,  and  not  an  isomorphous  sulphide.  It  has  been  detected 
in  the  metallic  state,  in  a  thin  section  of  a  pyrite  crystal  from 
Douglass  Island,  Alaska,  as  later  set  forth  (2.13.13,)  and  the 
fact  that  it  remains  as  the  metal  when  the  pyrite  is  dissolved 
in  nitric  acid  makes  this  undoubtedly  the  general  condition. 
The  association  of  gold  writh  bismuth,  v^^hich  has  been  shown 
by  R.  Pearce  to  occur  in  the  sulphurets  of  Gilpin  County, 
Colorado  (referred  to  on  p.  30G),  and  the  difficulty  experi- 
-enced  in  amalgamating  som^  ores,  indicate  the  possibility  of 


Pig.  145. — Section  of  the  Pittsburg  vein,  ninth  level,  Nevada  City  district, 

Cal.     XVIL  Ann.  Rep.  U.  S.  Geol.  Survey,  Part  IL,  p.  304, 

reduced  one  half. 


other  combinations.  When  crystallized,  gold  has  shown,  in 
one  specimen  and  another,  nearly  all  the  holohedral  forms  of 
the  isometric  system,  but  the  octahedron  and  rhombic  dode- 
cahedron are  commonest. 

2.12.19.  The  veins  are  younger  than  the  igneous  rocks  with 
which  they  are  associated.  Granite  and  grano-diorite  are  espe- 
cially frequent,  but  diorite,  gabbro,  diabase,  porphyrite  and 
serpentine,  presumably  derived  from  some  basic  intrusion,  are 
also  met.  Although  Von  Richthofen  stated  that  the  veins  sel- 
<dom  occur  far  from  granite,  this  has  been  shown  by  Lindgren  to 


366 


KEMP'S  ORE  DEPOSITS. 


be  unjustified.  The  greater  number  are  in  slates,  and  the- 
richest  in  a  particular  series  of  slates,  but  they  also  cut  all  man- 
ner of  igneous  rocks  and  have  no  constancy  of  direction.     Na 


SECTION  B-B 


'mmmm^'m^ 


<^^ 


'/^////////////^/////mv//^^^^ 


Fig.  146. — Oeological  section  at  the  Merrifidd  vein;  Providence  claim,  Nevada 

City  district,  Cal.     After ^W.  Lindgren,  XVIL  Ann.  Rep.  U.  8.  Oeol. 

Survey,  Part  II. ,  Plate  XXI ,  slightly  reduced. 

sharp  line  divides  them  from  silver-gold  veins,  which  occasion- 
ally occur  in  the  distinctive  gold  belt  nor  from  the  veins  earlier 


Fig.  147. — Cross- section  of  vein  in  St.  John  mine,  fifth  level,  Nevada  City  dis- 
trict, Gal.     After  If.  Lindgren,  XVII.  Ann.  Rep.  U.  S. 
Oeol.  Survey,  Part  II.,  p.  223. 

described  in  eastern  California  (2.12.07),  but  still  the  gold- 
quartz  type  is  in  characteristic  examples  sufficiently  pronounced 
to  justify  its  special  treatment.     The  close  relationships  that 


THE  PACIFIC  SLOPE. 


367 


prevail  between  pegmatite  dikes  or  veins,  at  one  extreme  and 
quartz  veins  at  the  other,  in  many  parts  of  the  world,  and  the 
occasional  auriferous  character  of  true  pegmatites,  may  be  sug- 
gestive as  throwing  light  on  their  nature  and  origin,  especially 
in  regions  of  intrusive  granite. 

While  igneous  dikes  often  form  one  wall  and  slate  the  other, 
the  source  of  the  ore  has  been  placed  by  our  best  observers  in 
deep-seated  regions,  whence  the  uprising  solutions  have  brought 
it.  Lateral  secretion  finds  slight  support  and  the  character  of 
the  walls  has  exercised  small  influence,  yet  the  presence  of  igne- 
ous rocks  is  in  the   large   way  favorable,  because  indicating 


Fig.  148. — Cross-section  of  the  Maryland  vein,  in  slopes  above  the  l^QQ-foot 

level,  Grass  Valley  district,  Cal.    After  W.  Lindgren,  XVII. 

Ann.  Rep.  U.  S.  Geol.  Survey,  Part  II,  p.  326, 

slightly  reduced. 

thermal  conditions  at  depths,  which  have  stimulated  mineral- 
bearing  circulations, 

Fairbanks  has  thought  that  evidence  of  the  replacement  of  the 
wall  rocks  could  be  noted,  but  Lindgren  controverts  this  view 
and  refers  them  to  the  filling  of  actual  cavities.  As  a  rule, 
they  are  not  much  broader  than  two  or  three  feet,  although  a 
network  of  small  veins  and  even  solid  quartz  may  extend  over 
a  much  greater  width,  and  the  gold  may  to  a  considerable  de- 
gree impregnate  the  wall-rock.  In  the  case  of  a  considerable 
width  of  pure  quartz,  say  20  or  30  feet,  an  original  cavity  of 
this  size  is  thought  improbable  by  Fairbanks,  who  cites  such 


368 


KEMP'S  ORE  DEPOSITS. 


veins  a^  strong  indications  of  replacement.  That  some  gold- 
bearing  ore  bodies,  which  depart  from  the  typical  quartz  vein, 
have  been  deposited  by  replacement  is  also  maintained  by  H. 
W.  Turner^  vs^hu  mentions  the  Diadem  lode,  southwest  of  Meadow 
Valley,  Plumas  County,  which  appears  to  be  a  bed  of  limestone 
or  dolomite  chiefly  replaced  by  gold-bearing  quartz  and  chal- 
cedony, but  in  such  a  way  that  fossil  foraminifera  are  still 
identifiable  in  the  ore.  Turner  also  mentions  a  number  of  albitic 
dikes,  of  which  one  at  the  Shaw  mine  is  described  in  the  next 
paragraph,  and  which  are  impregnated  with  gold-bearing  pyrites 


Fig.  149. — Cross-section  of  the  Brunswick  vein,  on  the  lOO-foot  level,  Grass 

Valley  district,  Cal.     After  W.  Lindgren,  XVII.  Ann.  Rep. 

U.  ^'.  Geol.  Survey,  Part  II.,  p.  230. 


of  low  grade.  The  latter  has  partly  entered  cracks  and  partly 
impregnated  the  rock  itself.  In  connection  with  replacement, 
however,  Lindgren  has  acutely  remarked  that  siliceous  replace- 
ments exhibit  either  a  very  fine-grained  aggregate  of  minute 
quartz  crystals  or  else  chalcedony,  both  quite  different  from  the 
coarsely  crystalline  quartz  of  the  typical  veins. 

2.12.20.  In  rare  instances  the  gold  is  associated  with  some 
other  gangue  than  quartz.  Thus  in  Vol.  XIII. ,  p.  24,  of  the 
Tenth  Census^  G.  F.  Becker  records  gold  in  calcite,  in  the 
Mad  Ox  mine  of  Shasta  County,  where  the  hanging  wall  is  a 

*  H.  W.  Turner,  "  Replacement  Ore  Deposits  in  the  Sierras,"  Jour.  Geol., 
Mav-June,  1899,  389. 


THE  PACIFIC  SLOPE.  369 

siliceous  limestone.  J.  S.  Diller  has  cited  a  similar  case  from 
Minersville,  Trinity  Coimty.  The  gold  occurred  in  veinlets  of 
calcite  in  a  dark,  carbonaceous  shale  {Amer.  Jour.  Sci.,  Feb- 
ruary, 1890,  p.  160).  Waldemar  Lindgren^has  described  an  in- 
stance in  which  gold  with  some  silver  occurred  in  seams  of  barite, 
which  were  themselves  in  a  kaolinized  zone  in  diabase  and  dia- 
base-porphyrite.  In  the  kaolin  0.34%  BaSO*  was  determined 
by  analysis.  It  may  have  been  derived  from  the  feldspar  of 
the  original  diabase.  W.  F.  Hillebrand^  has  lately  shown 
the  wide  distribution  of  both  barium  and  strontium.  Lind- 
gren^  has  also  written  of  most  remarkable  veins  at  Meadow 
Lake  in  Nevada  County,  that  contain  auriferous  sulphides  and 
arsenides  in  a  gangue  of  tourmaline,  quartz  and  epidote  in 
granitic  and  dia basic  rocks.  This  aggregate  suggests  fuma- 
Tolic  action.  Similarassociationsof  gold  with  tourmaline  have 
been  met  in  the  Zoutpansberg  District,  South  Africa,  and  in 
Brazil,  as  earlier  noted.  Through  the  kindness  of  Mr.  Leo 
von  Rosenberg,  the  writer  has  had  an  opportunty  to  examine 
a  suite  of  ores  from  the  Shaw  mine,  El  Dorado  County,  which 
have  been  donated  to  the  School  of  Mines,  Columbia  Univers- 
ity. The  same  had  been  previously  studied  by  H.  W. 
Turner,  of  the  U.  S.  Geol.  Survey,  by  whom  the  determina- 
tions were  originally  made.  The  mine  is  based  on  a  dike  of 
porphyrite,  sixty  or  seventy  feet  thick  and  charged  with 
pyrites.  It  is  auriferous  throughout,  but  richest  next  the  walls. 
The  gold  in  the  native  form  occurs  in  veinlets  of  albite,  which 
ramify  through  the  porphyrite.  An  analysis  by  Mr.  Hille- 
brand      established     the     identity     of    the     albite.*      T.    A. 

^  W.  Lindgren,  "The  Gold  Deposit  at  Pine  Hill,  California,"  Amer. 
Jour.  Sci.,  August,  1892,  p.  91. 

^  W.  F.  Hillebrand,  "  The  Widespread  Occurrence  of  Barium  and  Stron- 
tium in  Rocks,"  Jour.  Amer.  Chem.  Soc,  February,  1894,  p.  81. 

^  W.  Lindgren,  "The  Auriferous  Veins  at  Meadow  Lake,  California," 
Amer.  Jour.  Sci.,  September,  1893,  201. 

*  Since  the  above  was  written  Mr.  Turner  has  published  the  results  of 
his  examination  of  this  ore,  as  well  as  many  additional  important  notes  on 
the  associates  of  the  gold.  (H.  W.  Turner,  "Notes  on  the  Gold  Ores  of 
California,"  Amer.  Jour.  Set.,  June,  1894,  p.  467.)  Mr.  Turner  also  cites 
gold  in  quartz  in  rhyolite,  and  gold  with  cinnabar.  For  a  cross  section 
of  the  mine,  see  E.  E.  Olcott,  Tmus.  Amer.  Inst.  Min.  Eng.,  XXIV.,  883. 
Other  notes  appear  in  a  paper  by  C.  A.  Aaron,  Eng.  and  Min.  Jour.,  No- 
vember 19,  1892,  and  in  a  paper  in  the  Amer.  Geol,  XVII.,  380,  1896. 


370  KEMP'S  ORE  DEPOSITS. 

Rickard^  has  called  attention  to  the  especial  abundance  of  gold 
at  the  intersection  of  small  quartz  veins  in  Tuolumne  and  Cal- 
averas counties,  California,  and  to  the  occurrence  of  a  particu- 
larly rich  pocket  in  the  Rathgeb  mine,  San  Andreas,  where  a 
small  vein  was  faulted  a  few  inches,  and  where  the  gold  was 
associated  with  pitch-blende  or  uraninite  and  uranium  ochre.  ^ 
W.  H.  Storms  describes  the  Alvord  mine  in  San  Bernardino 
County  where  the  gold  occurs  with  a  siliceous  limonite  in 
chutes  in  a  belt  of  limestone.^  Storms  in  the  citations  given 
below  records  a  great  variety  of  wall  rocks  in  which  the  veins 
occur,  as  well  as  interesting  mineralogical  details. 

2.12.21.  The  formation  of  much  the  greater  number  of  the 
veins  followed  the  intrusion  of  the  grano-diorite,  which  oc- 
curred at  the  close  of  the  Jurassic  or  in  early  Cretaceous  time. 
Some,  however,  may  have  existed  before  this,  as  is  shown  by 
Lindgren's  interpretation  of  the  Jurassic,  auriferous  conglomer- 
ate, earlier  cited,  and  a  great  series  of  veins  certainly  followed 
the  Tertiary  igneous  outbreaks  in  the  high  Sierras.  It  seems 
quite  indisputable,  as  advocated  by  Lindgren,  that  the  gold 
and  its  associated  minerals,  including  the  quartz  gangue  canje 
up  in  heated  alkaline  solution,  and  that  the  vein  formation 
was  attended  by  extended  carbouatization  of  the  walls.  The 
deposition  of  the  silica  had  slight  chemical  effect  on  the  wall 
rock  in  other  respects,  for  the  change  of  the  latter  to  carbonates 
is  the  chief  alteration  visible.  The  enormous  introduction  of 
silica  is  one  of  the  most  extraordinary  features  of  the  geology 
of  the  Sierras,  and  indicates  a  remarkable  activity  of  circulat- 
ing waters. 

The  igneous  intrusions  doubtless  promoted,  if  they  did  not 
cause,  the  circulations.*    While  the  gold  is  often  entangled  in 

*  T.  A.  Rickard,  ''Certain  Dissimilar  Occurrences  of  Gold-bearing 
Quartz,"  Proc.  Colo,  Sci.  Soc,  September,  1893,  pp.  6-9. 

^  Henry  I^ewis  has  given  a  very  complete  review  of  the  associates  and 
occurrence  of  gold  in  the  Mineralogical  Mag.,  X.,  241,  London,  1898. 

'^  W.  H.  Storms,  "The  Wall  Rocks  of  California  Gold  Mines,"  Eng.  and 
Min.  Jour.,  February  23,  1895,  172.  ^ 

*  F.  Alger,  "Crystallized  Gold  from  California,"  ^mer.  Jbl^r.  Sci.,  ii., 
X.,  101.  M.  Attwood,  "On  the  Wall  Rocks  of  California  Gold  Quartz  and 
the  Source  of  the  Gold."  Rep.  Cal.  State  Mineralogist.  1888,  p.  771  (thought 
to  be  due  to  igneous  injection  in  diabase).  W.  P.  Blake,  "On  the  Par- 
allelism  between  the  Deposits  of  Auriferous  Drift  of  the  Appalachian 


THE  PACIFIC  SLOPE.  371. 

pyrite,  and  while  it  appears  to  have  been  associated   with  this 
iron  compound  in  its  precipitation,  yet  it  also  seems  to  have 
certainly  been  precipitated  in  the  native  state  in  many  instances 
2.12.22.     The  chemical  reactions  involved  in  the  introduc- 

Gold  Field  and  those  of  California,"  Amer.  Jour.  Sci.,  ii.,  XXVI.,  128. 
"Remarks  on  the  Extent  of  the  Gold  Region  of  California  and  Oregon," 
etc.,  Ibid.,  ii.,  XX.,  73.  "The  Carboniferous  Age  of  a  Portion  of  the 
Gold-bearing  Rocks  of  California,"  Ibid.,  ii.,  XLV.,  264.  W.  H.  Brewer, 
reply  to  above,  76zc?.,  ii.,  XLV.,  397.  A.  Bowman,  "Geology  of  the  Sierra 
Nevada  in  relation  to  Vein  Mining,"  Mm.  i^esoitrces  West  of  the  Rocky 
Mountains,  1875,  p.  441.  W.  H.  Brewer,  "  On  the  Age  of  the  Gold-bear- 
ing Rocks  of  the  Pacific  Coast,"  Amer.  Jour.  Sci.,  ii.,  XLII.,  114.  F.  G. 
Corning,  "The  Gold  Quartz  Mines  of  Grass  Valley,  California,"  Eng.  and 
Min.  Jour.,  December  11,  1886,  p.  418.  W.  M.  Courtis,  "  Gold  Quartz, " 
Trans.  Amer.  Inst.  Min.  Eng.,  XVIII.,  639.  H.  W.  Fairbanks,  "Geology 
of  the  Mother  Lode,"  Tenth  Ann.  Rep.  Cat.  Min.;  also  in  briefer  form  in 
Amer.  Geol,  April,  1891,  p.  201.  Rec.  "  On  the  Pre-Cretaceous  Rocks  of 
the  California  Coast  Ranges,"  ^mer.  Geol.,  March,  1892;  February,  1893. 
"  The  Relation  between  Ore  Deposits  and  their  enclosing  Walls, "  Eng.  and 
Min.  Jour.,  March  4,  1893,  200.  J.  H.  Hammond,  "  Mining  of  Gold  Ores 
in  California,"  Tenth  Ann.  Rep.  State  Min.,  p  852.  .Rec.  P.  Laur,  "Du 
Gisement  et  de  I'Exploration  de  I'Or  en  Californie,"  Ann.  des  Mines, 
Vol  III.,  1863,  p.  412.  W.  Lindgren,  "  The  Gold  Deposit  at  Pine  Hill,  Cal- 
ifornia," Amer.  Jour.  Sci.,  August,  1894,  92.  "The  Auriferous  Veins  of 
Meadow  Lake,  California,"  Idem,  September,  1893,  201.  "Characteristic 
Features  of  California  Gold  Quartz  Veins,"  Bidl.  Geol.  Soc.  of  Amer.,  VI., 
221,  1895.  Rec.  "  The  Gold-Silver  Veins  of  Ophir,  California,"  Ann.  Rep. 
Dir.  U.  S.  Geol.  Survey,  249,  1895.  Rec.  G.  W.  Maynard,  "Remarks  on 
Gold  Specimens  from  California,"  Trans.  Amer.  Inst.  Min.  Eng.,  VI.,  451. 
J.  S.  Newberry,  "On  the  Genesis  and  Distribution  of  Gold,"  School  of  Mines 
Quarterly,  III.,  p.  16.  E.  E.  Olcott,  "  On  the  Shaw  Mine,  Eldorado  Co.," 
with  a  cross  section.  Trans.  Amer.  Inst.  Min.  Eng.,  XXIV.,  883,  1894.  A. 
Remond,  "Mining  Statistics,"  No.  J,  Cal.  Geol.  Survey  (tabular  state- 
ment of  quartz  mining  and  mills  between  the  Merced  and  Stanislaus 
Rivers).  J.  A.  PhiUips,  "Mining  and  Metallurgy  of  Gold  and  Silver," 
also  treatise  on  Ore  Deposits,  p.  254.  Rec.  C.  M.  Rolker,  "The 
Late  Operations  in  the  Mariposa  Estate,"  Trans.  Amer.  Inst.  Min. 
Eng.,  VI.,  145.  B.  Silliman,  "Notice  of  a  Peculiar  Mode  of  Occurrence  of 
Gold  and  Silver  in  the  Foothills  of  the  Sierra  Nevada,  California,"-  Anner. 
Jour.  Sci.,  ii.,  XLV.,  92;  Cal.  Acad.  Sci.,  Vol.  III.,  p.  353.  W.  H.  Storms, 
"  The  Wall  Rocks  of  California  Gold  Mines,"  Eng.  and  Min.  Jour.,  Feb- 
ruary 23,  1895,  172.  H.  M.  Turner,  review  of  recent  papers  by  H.  W. 
Fairbanks  and  others  on  California  geology,  in  Amer.  Geol. ,  June,  1893. 
Rec.  J.  D  Whitney,  Cal.  Geol.  Survey,  Geology,  Vol.  I.,  p.  212.  J.  S. 
Wilson,  "  On  the  Gold  Regions  of  California,"  Quar.  Jour.  Geol.  Soc,  Vol 
X.,  p.  308,  1854. 


372  KEMP'S  ORE  DEPOSITS. 

tion  and  precipitation  of  gold  in  its  characteristic  veins  have 
been  the  subject  of  consideration  and  investigation  by  many 
observers,  especially  in  Australia.  The  almost  invariable  asso- 
ciation of  the  gold  with  silica;  its  very  frequent  entanglement 
in  iron  pyrites,  and  the  possibility  of  its  chemical  combination 
with  iron  pyrites  through  the  medium  of  silver  or  bismuth  or 
tellurium,  are  all  important  factors  to  be  considered.  The  exist- 
ence of  silicate  of  gold  was  early  shown  by  Bischoff,  who  did 
not  fail  to  appreciate  the  possibility  of  its  having  played  an 
important  part  in  the  filling  of  veins. ^ 

The  solubility  of  gold  in  solutions  of  ferric  sulphate  is  well- 
established,  although  the  amount  taken  up  is  small.  If  such 
auriferous  solutions  were  to  be  exposed  to  a  reducing  action, 
auriferous  pyrites  would  be  a  natural  result.  Experiments  by 
Richard  Pearce^  have  indicated  that  when  pure  gold  is  fused 
with  pyrites  it  still  remains  as  globules  through  the  resulting 
matte,  but  if  alloyed  with  silver,  bismuth  or  tellurium,  it  ap- 
parently combines  with  the  pyrites,  or,  at  all  events,  becomes 
invisibly  disseminated  in  it.  The  demonstrated  presence  of 
bismuth  and  tellurium  in  some  auriferous  pyrites  as  mined 
and  the  peculiar  metallurgical  behavior  of  such  ores  give  good 
reason,  as  Mr.  Pearce  has  pointed  out,  for  suspecting  that  the 
bismuth  and  tellurium  have  exerted  a  strong  influence  in  the 
original  precipitation  of  the  gold.  Again,  the  wide  distribu- 
tion of  haloid  salts  in  Nature  and  the  notable  solubility  of 
the  haloid  compounds  of  gold,  gives  this  group  of  elements  no 
small  theoretical  importance.  Taken  in  connection  with  alka- 
line salts,  especially  carbonates  and  sulphides,  the  former  of 
which  is  an  active  solvent  of  silica,  considerable  light  may 
be  thrown  on  the  chemistry  of  vein-formation.  Thomas 
Egleston'  has  recorded  interesting  experiments  upon  the  solu- 
bility of  gold  in  ammoniacal  compounds,  and  as  these    are 

*  Gustav  Bischofif,  "Lehrbuch  der  Chemischen  und  physikalischen  Geol 
ogie,"  Edition  1854,  II.,  36te-2657;  Edition  1866,  III.,  843-846.  The 
passage  is  omitted  in  the  English  translation  published  by  the  Cavendish 
Society. 

^  Richard  Pearce,  "The  Association  of  Gold  with  other  Metals  in  the 
West,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVIII.,  447,  1890.  Idem,  XXII., 
738. 

*  T.  Egleston,  "The  Formation  of  Gold  Nuggets  and  Placer  Deposits," 
Trans.   Amer.  Inst.  Min.  Eng.,  IX.,  633,  especially  639,  1881. 


THE  PACIFIC  SLOPE.  ,  373 

thought  by  G.  F.  Becker  to  have  been  factors  in  the  production 
of  the  cinnabar  deposits  of  California  (see  2.15.03),  the 
reactions  may  be  suggestive.  Of  the  haloid  elements,  iodine 
has  been  given  particular  prominence  by  several  observers, 
notably  T.  A.  Rickard.^  Where  a  reducing  action  is  required, 
organic  matter  in  the  wall  rocks  is  the  most  available  precipi- 
tating agent.  William  Nicholas  had  laid  stress  upon  its  im- 
portance.^ Below  is  given  a  list  of  the  other  principal  papers 
bearing  on  this  subject/  but  attention  may  also  be  directed  to 
the  general  literature  of  California  gold  deposits  on  a  previous 
page.  Considerable  difference  of  opinion  prevails  as  to 
whether  the  gold  has  come  from  a  fine  dissemination  in  the 
marine  sediments,  which  received  it  from  the  ocean,  during 
their  deposition,  or  whether  from  igneous  rocks,  from  which  it 
has  been  dissolved.  Gold  has  certainly  been  demonstrated  to 
exist  in  appreciable  quantities  in  sea-water^  and  also  to  have 
been  produced  by  crystallization  directly  from  an  igneous 
magma.* 

As  bearing  upon  this  last-named  point  an  extraordinarily 
thorough  and  patient  investigation  has  been  carried  through 
by  Mr.  John  R.  Don,  of  Otago,  New  2iealand,  the  object 
of  which  was  to  demonstrate  by  actual  chemical  analysis 
and  assay,  the  source  of  the  gold  in  certain  Australian 
reefs.  Vein  matter,  country  rocks,  sea- water,  in  fact,  all 
the  possible  and  available  sources  of  gold,  were  subjected 
to  quantitative  analysis.  The  results  were  so  largely 
negative,  that  the  author  feels  compelled   to  go  back  to  the 

*  T.  A.  Rickard,  "  Origin  of  the  Gold-bearing  Quartz  of  the  Bendigo 
Reefs,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXII.,  289,  1893,  and  discussion, 
p.  738. 

»  William  Nicholas,  "The  Origin  of  Gold  in  Certain  Victorian  Reefs," 
Eng.  and  Min.  Jour.,  December  15,  1883. 

^  A.  Liversidge,  "On  the  Amount  of  Gold  and  Silver  in  Sea  Water," 
Proc.  Roy.  Soc.  New  South  Wales,  October  2,  1895.  See  also  Chemical 
News,  September  and  October,  1896,  147,  160,  166;  Muenster,  Jour.  Soc. 
Chem.  Industry,  April  30,  1892,  XI.,  351.  E.  Sonstadt,  "  On  the  Presence 
of  Gold  in  Sea  Water,"  Idem,  October  4,  1872,  p.  159. 

*  W.  P.  Blake,  "Gold  in  Granite  and  Plutonic  Rocks,"  Trans.  Amer. 
Inst.  Min.  Eng.,  September,  1896.  G.  P.  Merrill,  "Gold  in  Granite," 
Amer.  Jour.  Sci.,  April,  1896,  309.  W.  Moericke,  "Notes  on  Chilean  Ore 
Deposits,"  Tschermak's  Mineralogischeund  Petrographische  Mitth.,  XIL, 
195. 


374  KEMP'S  ORE  DEPOSITS. 

deep-seated  sources  and  to  refer  the  gold  to  a  home  in  some 
rock,  not  available  for  assay.  Too  much  commendation  can 
scarcely  be  given  to  the  thoroughness  and  care  with  which  the 
investigation  was  carried  out.  The  quantitative  data  have 
placed  mining  geologists  the  world  over  under  a  great  debt.^ 

2.12.23.  The  stratigraphy  of  the  auriferous  strata  in  the 
Sierras  was  briefly  referred  to  above  as  involving  Paleozoic 
and  Mesozoic  strata.  It  would  be  impossible  and  undesirable 
to  give  in  this  place  any  complete  bibliography  of  the  subject, 
but  in  the  papers  of  Diller,^  J.  P.  Smith^  and  Turner,*  cited 
below,  quite  full  references  are  to  be  found  to  earlier  work.  In 
the  atlas  sheets  of  the  U.  S.  Geol.  Survey  local  names  are  given 
to  the  various  formations,  which  are  classified  on  the  physical 
basis  as  outlined  in  the  introduction  (1.01.01),  but  as  regards 
geological  time,  strata  have  been  identified  as  follows :  Pre- 
Silurian  crystalline  schists;  Silurian  quartzite  and  slate, 
with  included  lenses  of  limestone;  Devonian  coralline 
limestone;  probably  both  Lower  and  Upper  Carbonif- 
erous argillite,  quartzite,  mica-schist,  and  metamor- 
phosed tufiFs;  various  Triassic  and  Jura-Trias  sediments 
more  or  less  metamorphosed;  Jurassic  slates;  Cretaceous 
(Chico)  sandstone;  Tertiarj^  and  Quaternary  sandstone,  sands, 
gravels  and  clays.  (See  pp.  228-249  of  first  paper  of  H.  W. 
Turner,  cited  below.     Also  Diller  op.  cit.) 

In  the  auriferous  belt,  J.  P.  Smith  has  admitted  the  presence 
of  Silurian,  Carboniferous,  Triassic  and  Jurassic  strata,  but 
rejects  Cretaceous. 

2.12.24.  Our  knowledge  has  also  increased  of  la#fce  regarding 
the  intrusions  of  granite  and  the  relations  of  the  various  sedi- 
mentary formations  to  the  old  basement  upon  which  they  were 
laid  down.     The  work  of  H.  W.  Fairbanks,  often  cited  in  the 

*  John  R.  Don,  ' '  The  Genesis  of  certain  AAiriferous  Lodes, "  Trans. 
Amer.  Inst.  Min.    Eng.,  XXVII.,  564,  1897. 

'^  J.  S.  Diller  and  Charles  Schuchert,  "Discovery  of  Devonian  Rocks  in 
California,"  Amer  Jour.  Sci.,  June, -1894,  416. 

'  J.  P.  Smith,  "  Age  of  the  Auriferous  Slates  of  the  Sierra  Nevada," 
Bull.  Geol.  Soc.  Amer.,  V.,  243,  1894. 

*  H.  W.  Turner,  "Geological  Notes  on  the  Sierra  Nevada."  Amer.  Geol., 
April  and  May,  1894,  228-297.  Further  contributions  to  the  "Geology  of 
the  Sierra  Nevada,"  XVII  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey,  521-740. 
"  Granitic  Rocks  of  the  Sierra  Nevada,"  Jour,  of  Geol,  March,  1899.  141. 


THE  PACIFIC  8L0PE.  375 

text,  and  that  of  the  U.  S.  geologists,  Becker,  Diller,  Turner 
and  Lindgren,  have  been  bringing  out  forcibly  the  intrusive 
nature  and  Mesozoic  age  of  much  of  the  granite  of  the  Sierras 
and  of  the  Coast  range.  Most  recently  among  the  Canadians 
G.  M.  Dawson  has  traced  similar  effects  to  the  north,  and  A. 
C.  Lawson,^  from  an  extended  survey  of  the  western  coast,  and 
search  in  the  literature  of  Mexico,  Central  and  even  South 
America,  forcibly  portrays  the  advance  of  the  great  granitic 
"batholites"  {i.e.,  plutonic  masses)  toward  the  surface,  the 
fusing  into  their  magmas  of  the  overlying  strata,  and  the 
metamorphic  effects.  All  these  cannot  but  be  strong  factors  to 
be  considered  in  connection  with  the  ore  bodies,  and  as  time 
goes  on  this  connection  will  probably  be  shown. 

In  regard  to  the  other  forms  of  igneous  rocks  involved  in  the 
gold  belt  and  often  greatly  metamorphosed,  we  are  advancing 
rapidly  in  knowledge.  These  were  referred  to  earlier  under 
2.12.19,  but  in  his  review  of  the  igneous  rocks  Mr.  Turner^ 
cites  nearly  the  entire  series  of  plutonic  and  effusive  types.  In 
many  instances  the  more  basic  members  have  passed  under  the 
influence  of  dynamo-metamorphism,  into  amphibolites  and 
talcose  rocks,  but  in  other  cases  the  dikes  and  sheets  are  still 
little  if  at  all  changed.  Great  areas  are  formed  of  them  or 
involve  them,  and  lead  to  the  inference  that  they  have  not  been 
without  their  influence  in  promoting  ore- bearing  circulations. 

Mr.  Turner's  recent  review  of  the  geology  of  the  Sierras^  is 
important,  not  alone  in  its  bearings  on  local  geology,  but  upon 
theoretical  petrology  as  well.  The  folios  of  the  U.  S.  Geologi- 
cal Survey  now  embrace  a  large  portion  of  the  gold  belt,  and 
are  much  the  most  available  expositions  of  the  geological 
structure.  They  are  listed,  so  far  as  yet  issued,  in  the  footnote 
to  paragraph  2.12.06. 

^  A.  C.  Lawson,  "The  Cordilleran  Mesozoic  Revolution,"  Journal  of 
Geology,  I.,  579,  1893. 

2  Amer.  Geol,  May,  1894,  pp.  297-316. 

3  XVIL  Ann.  Rep.  Dir.  U.  S.  Geol  Survey. 


CHAPTER  XIII. 

GOLD  ELSEWHERE  IN  THE  UNITED   STATES  AND  IN   CANADA. 

2.13.01.  Example  45a.  Southern  Appalachians.  Gold- 
quartz  veins  and  veinlets  and  auriferous  impregnations  of  the 
country  rocks,  which  are  almost  invariabl}'^  of  metamorphic 
types,  and  which  are  of  considerable  variety.  From  these, 
placers  have  resulted,  both  by  superficial  decay  and  by  erosion. 
The  general  geology  of  the  southern  Atlantic  States  has  been 
outlined  in  the  introduction.  Reference  may  again  be  made  to 
the  Coastal  Plain  of  Quaternary,  Tertiary,  and  Mesozoic  sedi- 
mentary strata,  and  to  the  crystalline  and  metamorphosed  belt, 
lying  west  of  it.  In  the  latter  are  found  the  gold  deposits. 
Increasing  observation  tends  to  show  that  the  quartz 
veins  are  all  fillings  of  fissures,  which  have  been  pro- 
duced in  the  geological  disturbances  to  which  the  region 
has  been  subjected.  The  smaller  reticulations  indicate 
crushings,  more  or  less  intimately  related  to  the  gen- 
eral production  of  schistosity,  but  the  larger  veins  often  cut  the 
schistosity  at  a  notable  angle  and  clearly  have  been  produced 
by  fairly  extended  dislocations.  All  are  deposited  in  what 
Posepny  has  called  "spaces  of  discission."  The  wall  rocks 
embrace  both  metamorphosed  sediments  and  metamorphosed 
igneous  rocks.  The  latter  are  both  of  volcanic  and  plutonic 
origin,  and  the  altered  volcanics  may  closely  resemble  slates. 
Foliation  is  everywhere  developed.  Dikes  of  diabase,  little,  if 
at  all,  metamorphosed,  are  present  in  some  districts  of  North 
Carolina,  and  have  certainly  exercised  a  favorable  influence  on 
the  ore  deposition.  In  all  parts  of  the  gold  territory  the  super 
ficial  decay  has  been  pronounced,  and  the  rocks  are  extensively 
decomposed  to  depths  that  may  reach  over  100  feet.  Such 
material  has  been  called  by  Becker,  saprolite,  meaning  by  the 


GOLD  m  UNITED  STATES  AND  CANADA.  377 

word  a  general  term  for  decomposed  rock,  whatever  has  been 
its  original  character.  Laterite  has  been  earlier  used  in  the 
same  sense  and  has  priority.  The  ores  are  oxidized  in  these 
decomposed  walls  and  the  whole  mass  may  be  hydraulicked, 
the  free  gold  being  caught,  and  the  boulders  of  gold  quartz 
being  concentrated  for  milling.  The  laterite  also  works  down 
hill  from  its  original  position,  and  has  been  called  in  this  con- 
nection * 'frost-drift"  by  Kerr.  Natural  erosion  has  led  to  the 
formation  of  the  usual  type  of  placers,  and  these  have  been 
worked  more  or  less  in  earlier  years,  and  are  still  productive  in 
a  small  way.  Above  the  level  of  the  ground- water  the  veins 
chiefly  afford  free  milling  ores,  but  below  it,  they  pass  into 
more  rebellious  sulphurets  of  the  usual  types.  The  mineralogy 
of  the  veins  is  similar  to  that  of  the  usual  run  of  gold-quartz 
veins,  but  in  the  aggregate  presents  considerable  variety. 
Becker  records  a  total  of  59  minerals,  of  which  45  are  original, 
and  14  secondary.  The  gold  is  at  times  found  in  the  country 
rock  along  quartz  veins,  and  sometimes  in  rock  free  from  vein 
formations,  but  it  is  presumably  of  secondary  introduction. 
The  garnets  of  a  mica-schist  near  Dahlonega,  Ga.,  have 
been  proved  by  Becker  to  be  notably  auriferous.^ 

^  The  following  papers  refer  to  the  gold  deposits  of  the  Southern  Appa- 
lachians in  general ;  subsequently  papers  are  grouped  by  States.  G.  F. 
Becker's  paper,  cited  below,  contains  a  quite  complete  bibliography,  pp. 
70-73,  chronologically  arranged,  down  to  1894.  Acknowledgments  are 
here  made  to  it,  but  additional  papers  are  also  given.  W.  H.  Adams,  "Gold 
Mining  in  the  Appalachian  Belt,"  Eng.  and  Min.  Jour.,  July  4,  1896,  p.  7. 
W.  R.  Balch,  **  Mines,  Miners  and  Mining  Interests  of  the  United  States," 
1882,  p.  1102.  G.  F.  Becker,  "Reconnaissance  of  the  Gold  Fields  of  the 
Southern  Appalachians,"  XVI.  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey,  Part 
II.,  1895.  Rec.  F.  C.  Hand,  "Southern  Gold  Fields,"  Eng.  and  Min. 
Jour.,  December  7,  1889,  p.  495.  W.  C.  Kerr,  "  On  the  Action  of  Frost  in 
the  Rearrangement  of  Superficial  Earthy  Material,"  Amer.  Jour.  Sci., 
XXI.,  1881,  345.  O.  M.  Lieber,  "A  Contribution  to  the  Geologic  Chronol- 
ogy of  the  Southern  Appalachians,"  Proc.  Am^r.  Assoc.  Adv.  Sci.,  XII., 
1859,  227.  P.  H.  Mell,  "  Auriferous  Slate  Deposits  of  the  Southern  Appa- 
lachians," Trans.  Amer.  Inst.  Min.  Eng.,  IX.,  399;  Eng.  and  Min.  Jour., 
June  11,  1881,  397.  H.  B.  C.  Nitze,  "  Present  Condition  of  Gold  Mining  in 
the  Southern  Appalachian  States,"  Idem,  XXV.,  661.  Discussion,  1021, 
1025.  Rec.  A  review  by  Robert  Peele  in  the  School  of  Mines  Quarterly, 
January,  1896,  177,  is  a  valuable  discussion.  See  also  forthcoming 
Bulletin  17,  N.  C.  Oeol.  Survey.  E.  G.  Spilsbury,  "Notes  on  the  General 
Treatment  of  the  Southern  Gold  Orcjs  and  Experiments  in  Matting  Iron 


378  KEMP'S  ORE  DEPOSITS. 

2.13.02.  Becker  has  broadly  divided  the  auriferous  area  into 
three  great  belts:  the  Georgian  belt,  extending  from  Montgom- 
ery, Ala.,  through  Dahlonega,  Ga.,  to  the  Boilston  Mine  in 
North  Carolina ;  the  South  Mountain  belt,  embracing  a  group  of 
mountains  of  this  name  in  North  Carolina;  and  the  Carolinian 
belt,  lying  far  to  the  east  of  the  latter  and  ranging  from  South 
Carolina  two-thirds  across  North  Carolina.  The  Virginia  de- 
posits lie  in  the  same  line  further  north.  So  far  as  North  Caro- 
lina is  concerned  this  classification,  as  shown  later,  has  been 
amplified  by  Nitze. 

2.13.03.  Alabama.  The  gold-bearing  belt  begins  in  Ala- 
bama on  the  southwest  and  covers  in  this  State  a  triangular 
area  some  90  miles  on  a  side  and  situated  about  the  middle  of 
the  eastern  boundary.  In  all  nine  counties  are  embraced.  The 
country  rock  consists  of  the  Talladega  series  of  slates,  quartz- 
ites,  conglomerates,  and  dolomites;  and  of  a  complex  series  of 
gneisses,  diorites,  green  schists,  granites  and  some  basic  dikes, 
besides  other  minor  varieties  of  rocks  of  igneous  affinities. 
The  Talladega  series  contains  a  large  proportion  of  the  gold 
mines,  but  others  are  known  in  the  gneisses,  diorites  and  green 
schists.      The  veins  are  commonly  parallel  to  the  foliation.^ 

Sulphides,"  Trans.  Amer.  Inst.  Min.  Eng.,  XV.,  767.  J.  W.  Taylor,  "The 
Gold  and  Silver  Mines  East  of  the  Rocky  Mountains,"  Amer.  Jour,  of  Min- 
ing,  II.,  390,  1867.  J.  D.  Whitney,  Metallic  Wealth  of  the  United  States, 
1854.  Volume  XIII.  of  the  Tenth  Census,  on  the  Precious  Metals,  has 
valuable  statistics,  and  the  volume  on  the  Mineral  Industries  of  the 
Eleventh  Census  has  later  ones. 

^  The  following  references  may  be  consulted  on  Alabama.  Attention  is 
also  called  to  the  general  references  in  the  preceding  footnote,  that  refer 
to  the  Southern  Appalachians.  Anonymous,  "Notes  on  the  Alabama  Gold 
Belt,"  Eng.  and  Min.  Jour.,  January  20,  1894,  p.  57.  W,  M.  Brewer, 
"The  Arbacoochee  Gold  District,  Ala.,"  Idern,  August  17,  1895,  148. 
W.  M.  Brewer,  "The  Gold  Regions  of  Georgia  and  Alabama,"  Trans. 
Amer.  Inst.  Min.  Eng.,  XXV.,  569.  "The  Upper  Gold  Belt  of  Alabama," 
Bulletin  5,  Alabama  Geol.k  Survey,  1896,  contains  supplementary  notes  by 
E.  A.  Smith,  and  valuable  petrographical  descriptions  by  J.  M.  Clements 
and  A.  H.  Brooks  ;  a  few  also  by  C.  W.  Havves.  Rec.  J.  L.  Campbell 
and  W.  H.  Ruffner,  "A  Physical  Survey  from  Atlanta,  Ga.,  across  Ala- 
bama and  Mississippi  to  the  Mississippi  River,  along  the  line  of  the  Georgia 
Pacific  R.  R.,"  New  York.  1883,  37.  O.  M.  Lieber  refers  at  length  to 
Alabama  placers  in  his  paper  on  "  Der  Itacolumit,  seine  Begleiter  und  die 
Metallfiihrung  desselben:  Gangstudien,"  III.,  especially  pp.  406  and  fol- 
lowing.    W.  B.  Phillips,  "  The  Lower  Gold  Belt  of  Alabama,"  Bulletin  3, 


GOLD  IN  UNITED  STATES  AND  CANADA.  379 

Geographically  the  gold  region  is  sometimes  divided  into  the 
Lower  Belt,  comprising  Coosa,  Tallapoosa,  Chambers  and  part 
of  Chilton  counties,  and  the  Upper,  in  Cleburne,  Clay,  Ran- 
dolph and  part  of  Talladega  counties. 

2.13.04.  Georgia.  The  metamorphic  areas  containing  the 
gold  of  Alabanca  are  continued  across  Georgia  in  a  northeasterly 
line,  with  a  general  strike  of  the  foliation  between  30  and  50 
degrees  N.  E.  The  dip  is  southeast.  Gneiss  and  schists  pre- 
vail, but  igneous  rocks  are  not  unknown.  Dahlonega  is  the 
chief  mining  center,  and  has  important  hydraulic  works  and 
stamp  mills  in  operation.^    The  decomposed  rock  is  hydrau- 


Alabama  Geol.  Survey,  1892.  Rec.  J.  W.  Spencer,  "  Economic  Geologi- 
cal Survey  in  Georgia  and  Alabama,  along  the  Macon  and  Birmingham 
Railroad,  1889"  (cited  by  G.  F.  Becker).  M.  Tuomey,  "  First  Biennial 
Report  on  the  Geology  of  Alabama,"  1847-1849,  1850.  Second  ditto,  1855, 
1858. 

^  Attention  is  called  to  the  general  papers,  earlier  cited .  Adelberg  and 
Raymond,  "Report  on  the  Lewis  Gold  Mine,"  1866,  "Report  on  the 
ONeil  Property,'  1866.  W.  P.  Blake,  "Report  on  the  Gold  Placers  of 
Lnmpkin  County,  Ga.,"  etc.  (small  book  published  by  J.  F.  Trow,  New- 
York,  1858).  See,  also,  Amer.  Jour.  Sci.,  ii.,  XXVI.,  378;  Mining  and  Statis- 
tical Magazine,  X.,  467,  476,  1858.  "On  Placer  Gold  Mines  in  Georgia,  ' 
etc.,  Proc.  Amer.  Assoc.  Adv.  Sci.,  1859.  "Notes  and  Recollections 
Concerning  the  Mineral  Resources  of  Northern  Georgia  and  Western  North 
Carolina,  '  Trans.  Amer.  Inst.  Min.  Eng.,  XXV.  796, 1895.  W.  H.  Brewer, 
"The  Dahlonega  Gold  Mining  District, "  Eng.  and  Min.  Jmir.,  December  15, 
1894,  559.  ' '  New  Work  in  the  Villa  Rica  District, "  Idem,  June  20,  1897.  H . 
Credner,  "  Beschreibung  einer  paragenetisch,  interessanter  Goldvorkom- 
men  in  Georgia,  Nord  Amerika,"  Neues  Jahrhuch,  1867,  443.  "  Geognos- 
tische  Skizze  der  Goldf elder  von  Dahlonega,  Georgia,  Nord  America," 
Zeitschr.  d.  d.  Geol.  Gesells.,  XIX.,  34,  1867.  C.  T.Jackson,  "Minerals 
from  Georgia,"  Proc.  Bost.  Soc.  Nat.  Hist.,  VII.,  22,  1861.  J.  B.  Mackin- 
tosh, "The  Gold  Mining  District  of  Dahlonega,  Ga.,"  Eng.  and  Min.  Jour., 
XXVII.,  258,  1879.  P.  H.  Mell,  "Papers  on  Gold  Mining  in  Georgia," 
Eng.  and  Min.  Jour.,  October  6  and  13,  1877,  pp.  238,  275  ;  also,  p.  528; 
August  10  and  17,  1878,  pp.  97,  116.  P.  C.  Morton,  "Mineral  Resom'ces  of 
Georgia,"  Amer.  Jour.  Mining,  I.,  265, 1866.  J.  Peck,  "The  Mining  Region 
of  Georgia,  Western  North  Carolina  and  East  Tennessee,"  Amer.  Jour. 
Sci.,  i.,  XXIII.,  4,  1883.  Wm.  Phillips,  "Essay  on  the  Georgia  Gold 
Mines,"  Idem,  l,  XXIV..  1.  C.  U.  Shepard,  "OnLazulite,  Pyrophyllite, 
and  Tetradymite  in  Georgia,"  Idem,  ii.,  XXVII.,  36, 1859.  J.  W.  Spencer, 
see  under  Alabama.  H.  G.  Torrey,  "  Tests  of  Dahlonega  Gold  Ores,"  Eng. 
and  Min.  Joui.,  January  5,  1895,  2.  "Yeates,  McCallie  and  King;  Gold 
Deposits  of  Georgia,"  Geol.  Survey  of  Georgia,  Bulletin  4,  1896. 


380  KEMP'S  ORE  DEPOSITS. 

lir,ked,  the  quartz  boulders  are  caught  and  are  then  run  through 
stamps. 

2. 13.05.  South  Carolina.  The  mines  in  this  State  are  on  the 
southern  extension  of  the  Carolinian  belt  in  Lancaster,  Ches- 
terfield and  Union  counties.  The  Haile  is  one  of  the  best 
known,  and  affords  an  ore  consisting  of  impregnated  muscovite 
schist,  that  is  an  altered  pre-Cambrian  volcanic,  according  to 
Becker.  The  rich  portions  occur  along  intruded  diabase  dikes. 
The  Brewer  mine,  a  few  miles  away,  has  similar  wall  rock.^ 

2. 13.06.  North  Carolina.  The  Georgian  belt  of  Becker  just 
reaches  North  Carolina,  the  South  Mountain  belt  lies  wholly 
within  it,  and  the  Carolinian  belt  passes  through  its  eastern  or 
eastern  central  portion.  Nitze  and  Hanna  divide  the  gold- 
bearing  areas  of  the  State  into  six  belts,  which  are  from  east  to 
west.  (1)  The  eastern  Carolina  belt,  in  Warren,  Halifax,  Frank- 
lin and  Nash  counties.  Quartz  vein  lets  are  found  in  diorite, 
chlorite  schist  and  gneiss.  (2)  The  Carolina  slate  belt,  ex- 
tending southwest  across  the  State  from  Person  to  Union  coun- 
ties. The  mines  are  mostly  in  Randolph,  Davidson,  Montgom- 
ery, Stanley  and  Union  counties.  The  wall  rocks  are  slates 
and  volcanics.  Diabase  dikes  exert  a  favorable  influence. 
(3)  The  Carolina  igneous  belt,  chiefly  in  Mecklenburg, 
Cabarrus,  Rowan,  Davidson  and  Guilford  counties.  The  rocks 
are  granite,  diorite,  gabbro  and  diabase,  and  are  later  than  the 
slates.  The  gold -quartz  veins  often  carry  copper.  (4)  The 
King's  Mountain  belt,  in  Gaston,  Lincoln,  Catawba,  Davie  and 
Yadkin  counties.  The  rocks  are  crystalline  schists,  gneisses, 
siliceous  limestones  and  quartzites.  The  ores  are  sometimes 
impregnated  streaks  of  country  rock,  and  again  are  quartz 
veins.     The  King's  Moimtain  mine  has  ores  in  siliceous  lime- 

*  Attention  is  called  to  the  general  papers  earlier  cited.  G .  E.  Ladshaw, 
"Spartanburg,  South  Carolina,  Gold  Fields,"  Eng.  and  Min.  Jour.,  July 
16,  1893,  52.  O.  M.  Lieber,  "Reports  of  the  Geological  Survey  of  South 
Carolina,"  1856,  1858,  1859,  1860.  "Gold  in  South  Carolina  "is  often  re- 
ferred to  in  Lieber's  paper  on  "  Itacolumit, "  etc.,  Gangstudien,  III.,  309, 
405,  ff.  R.  Mills,  "  Gold  Occurrences  in  South  Carohna,"  in  Statistics  of 
South  Carolina,  1826,  pp.  26,  671.  E.  G.  Spilsbury,  "Gold  Mining  in 
South  Carolina,"  Trans.  Amer.  Inst.  Min.  Eng.,  XII.,  99,  1884.  A.  Thies 
and  E.  Metzger,  "Geology  of  the  Haile  Mine,"  Idem,  XIX.,  595,  1890.  A. 
Thies  and  W.  B.  Phillips,  "The  Thies  Process,  etc.,  at  the  Haile  Mine," 
Idem,  XIX.,  601,  1890. 


GOLD  IN  UNITED  STATES  AND  CANADA.  381 

stone,  and  is  a  well-known  one.  (5)  South  Mountain  belt,  in 
Burke,  McDowell  and  Rutherford  counties.  The  rocks  are 
mica  and  hornblende  gneisses  and  schists,  with  pegmatites  and 
some  minor  pyroxenic  varieties.  Quartz  veins  in  true  fissures 
are  the  rule.  They  can  be  classed  into  five  sub-belts.  (6) 
Gold  deposits  west  of  the  Blue  Ridge  in  Ashe,  Jackson,  Tran- 
sylvania, Macon  and  Cherokee  counties.  The  rocks  are  gneis- 
ses and  schists  wth  quartz  veins.  The  Bulletin  by  Nitze  and 
Hanna,  cited  below,  gives  details  from  all  the  mines  of  the  State. ^ 
2.13.07.     Virginia,  Maryland  and  the  Northern  States. 

*  Attention  is  called  to  the  general  citations  earlier  given.  W.  P.  Blake, 
' '  Remarks  on  the  Minerals  and  Ancient  Mines  of  the  Cherokee  River 
Valley,  N.  C,"  Proc.  Amer.  Assoc.  Adv.  Sci.,  1859.  L.  S.  Burbank,  "Sur- 
face Geology  of  North  Carolina,"  Proc.  Bast.  Soc.  Nat.  Hist,  1873,  151. 
H.  M.  Chance,  "Auriferous  Gravels  of  North  Carolina,"  Amer.  Phil.  Soc, 
1881,  477.  H.  E.  Colton,  "Mining  in  North  Carolina,"  Eng.  and.  Min. 
Jour.,  1871.  323.  H.  Credner,  "  Report  of  Explorations  in  the  Gold  Fields 
of  Virginia  and  North  Carolina, "  Amer.  Jour,  of  Mining,  1868,  361,  377,  393, 
407.  W.  B.  Devereux,  ' '  Gold  and  Its  Associated  Minerals  at  King's 
Mountain,  N.  C,"  Eng.  and  Min.  Jour.,  January  15,  1881,  39.  M.  W. 
Dickeson,  ' '  Report  on  the  Brown  and  Edwards  Properties,"  1860.  "  Report 
on  the  Rhea  Mine,"  1860.  A.  Eaton,  "The  Gold  of  the  ^Carolinas  in  Tal- 
cose  Slate,"  Amer.  Jour.  Sci.,  i.,  XVIII.,  50,  1850.  E.  Emmons,  "Geolog- 
ical Report  upon  the  Midland  Counties  of  North  Carolina,"  1896.  F.  A. 
Genth,  "Contributions  to  American  Mineralogy,"  ^mer.  Jour.  Sci.,  ii.. 
XIX.,  18,  1855  ;  ii.,  XXVIII.,  246,  1859.  "Report  on  the  Stewart  Mine," 
1856.  See  Journal  of  the  Frankliii  Institute,  November,  December,  1871. 
"  Mineral  Resources  of  North  Carolina,"  in  Kerr's  Report.  1875,  Appendix 
O.  "The  Minerals  and  Minei'al  Localities  of  North  Carolina,"  printed  for 
the  State  Board  of  Agriculture,  Raleigh,  1885.  '  •  The  Minerals  of  North 
Carolina,"  Bulletin  74,  U.  S.  Geol.  Survey,  1891.  J.  H.  Gibbon,  "Letter 
on  the  Gold  of  North  Carolina,"  Amer.  Jour.  Sci.,  i.,  XLVIIL,  398,  1844. 
•F.  C.  Hand,  "Southern  Gold  Fields,"  Eng.  and  Min.  Jour.,  December  7, 
1889,  495.  G.  B.  Hanna,  "The  Fineness  of  Native  Gold  in  the  Carolinas 
and  Georgia,  '  Idem,  September  18,  1886,  201.  See,  also,  under  Kerr  and 
under  Nitze.  O.  J.  Heinrich,  "On  Gold  Hill,  N.  C,"  Trans.  Amer.  Inst. 
Min.  Eng.,  II.,  324,  1874.  J.  A.  Holmes,  "  Forthcoming  Bulletin  17,  North 
Carolina  Geological  Survey,  with  a  Geological  Bibliography,"  in  prepara- 
tion, 1897.  C.  L.  Hunter,  "Notice  of  the  Rarer  Minerals  and  of  New  Lo- 
calities in  Western  North  Carolina,"  Amer.  Jour.  Sci.,  ii.,  XV.,  375,  1853. 
C.  T.  Jackson,  "Report  on  the  McCuUock  Copper  and  Gold  Mining  Co.," 
1853.  W.  C.  Kerr,  "Geological  Report  on  North  Carolina."  1869  ;  ditto. 
1875.  "  Gold  Gravels  of  North  Carolina,"  Trans.  Amer.  Inst.  Min.  Eng., 
VIII.,  462.  "  Some  Peculiarities  in  the  Occurrence  of  Gold  in  North  Caro- 
lina." Idem,  X.,  475,  1882.     "On  the  Action  of  Frost  in  the  Arrangement 


382  KEMP'S  ORE  DEPOSITS. 

The  Carolinian  belt  of  Becker  extends  into  Virginia,  an.^.  ha& 
been  the  basis  of  some  mining.  The  usual  type  of  quartz  veinlets 
in  schists  is  met.  The  belt  runs  through  the  State  east  of  the 
Blue  Ridge. ^     Several  small  mines  have  been  developed   in 

of  Superficial  Earthy  Material,"  ^wier.  Jour.  Sci.,  iii.,  XXI.,  345,1881. 
S.  P.  Leeds,  "Reports  on  the  Karricker,  the  Rhymer,  and  the  Rudisill 
Mines,"  1854.  O.  M.  Lieber,  "Ueber  das  Gold-vorkommen  in  Nord  Caro- 
lina," Gangstudien,  III.,  253,  1860  ;  also,  417.  Jules  Marcou,  "On  Gold 
in  North  Carolina,  '  Proc.  Bost.  Soc.  Nat.  Hist.,  IX.,  47,1862.  A.  Metz- 
ger,  "The  Gold  Mines  of  North  Carolina,"  Eng.  and Min.  Jour.,  October, 
24,  1891,  480.  E.  Mitchell,  "On  the  Geology  of  the  Gold  Region  of  North 
Carolina,"  Amer.  Jour.  Sci.,  i.,  XVI.,  19,  1829.  H.  B.  C.  Nitze,  "The 
Genesis  of  the  Gold  Ores  in  the  Central  Slate  Belt  of  the  Carolinas,  '  Eng. 
and  Min.  Jour. ,  June  19, 1897.  H.  B.  C.  Nitze  and  G.  B.  Hanna,  • '  Gold 
Deposits  of  North  Carolina,"  Bidletin  3,  N.  C.  Geol.  Survey,  1897.  Rec. 
H.  B.  C.  Nitze  and  A.  J.  Wilkins,  "Gold  Mining  in  North  Carolina  and 
other  Appalachian  States,"  Bulletin  X.,  Idem  (in  preparation),  1897;  see. 
also.  Trans.  Amer.  Inst.  Min.  Eng.,  XXV.,  661.  D.  Olmstead,  "Gold 
Mines  of  North  CaroHna,"  Amer.  Jour.  Sci.,  i.,  IX.,  5,  1825.  C.  E.  Rothe, 
"Remarks  on  the  Gold  Mines  of  North  Carolina,"  Jdem,  i.,  XIII.,  201. 
1828.  C.  U.  Shepard,  "Report  on  the  Gold  Hill  Mine,"  1853.  "Gold  in 
North  Carolina,"  N.  Y.  Mining  Magazine,  X.,  271,  1858  ;  XI.,  136.  F.  L. 
Smith,  "Notice  of  Some  Facts  Connected  with  the  Gold  of  a  Portion  of 
North  Carolina,"  Amer.  Jour.  Sci.,  i.,  XXXII.,  130,  1837.  R.  P.  Stevens. 
"Gold  in  North  Carolina,"  Am^r.  Jour.  Min.,  I.,  313,  1866.  R.  C.  Taylor. 
"Report  on  the  Washington  Silver  Mine,"  1845.  P.  T.  lyson,  "Report 
on  the  Gold  Deposits  of  the  Mateo  Mining  Co.,"  1856.  Arthur  Winslow, 
"  Gold  Mines  in  North  Carolina,"  Eng.  and  Min.  Jour.,  XL.,  218,  1885. 

'  Attention  is  called  to  the  general  references  on  the  Southern  States, 
earlier  given.  J.  L.  Campbell,  "Geology  and  Mineral  Resources  of  the 
JamesRiver  Valley,"  p.  99,  New  York,  G.  P.  Putnam's  Sons,  1882.  Ab- 
stract in  Eng.  and  Min.  Jour.,  September  9,  1882,  135.  T.  G. 
Clemson,  "  The  Gold  Region  of  Virginia,"  Trans.  Geol.  Soc.  Penn..  309, 
1835.  H.  Credner,  "Report  of  Explorations  in  the  Gold  Fields  of  Virginia 
and  North  Carolina,"  Amer.  Jour,  of  Mining,  1868,  pp.  331,  377,  393,  407. 
"  Geognostische  Skizzen  aus  Virginia.  Nord  Amerika."  Zeitschr.  d.d. 
Geol.  Gesellsch,  1866,  83.  A.  Del  Rio,  "Report  on  the  Rappahannock 
Gold  Mine,  Virginia,"  1824.  E.  W.  Johnson,  "On  the  Garnett  Gold  Mine, 
Virginia,"  1852.  W.  R.  Johnson,  "  Some  Observations  on  the  Gold  For- 
mations of  Maryland,  Virginia,  and  North  Carolina,"  Proc.  Amer.  Assoc. 
Adv.  Sei.,  18.'i0,  IV.,  20.  M.  F.  Maury,  "Notice  of  Gold  Veins  of  the 
United  States  Mine,  near  Fredericksburg,  Va.,"  Amer.  Jour.  Sci.,  i., 
XXXII.,  325,  1837.  J.  H.  Morton,  "-Gold  Mines  in  Virginia,"  Eng.  and 
Min.  Jour.,  XXV.,  1878.  T.  Pollard,  on  Gold  in  Virginia,  see  Lock's 
"Gold:  Its  Occurrence  and  Extraction,"  1882,  182.  B.  Silliman,  "Re- 
marks on  Some  of  the  Gold  Mines  and  on  Parts  of  the  Gold  Regions  of 
Virginia,"  Amer.  Jour.  Set.,  l,  XXXII.,  98,  183,  185,  1837. 


GOLD  IN  UNITED  STATES  AND  CANADA.  383 

Maryland,  not  far  from  Washington/  and  a  few  indications  of 
gold  have  been  met  in  Pennsylvania/ New  Jersey,  New  York/ 
and  Massachusetts.*  In  the  metamorphosed  Cambrian  and 
Silurian  strata  of  Vermont  ^  quite  serious  attention  has  been 
given  to  both  veins  and  gravels.  Gold-bearing  mispickel  is 
known  in  New  Hampshire,*'  as  well  as  in  the  usual  quartz 
veins.  Some  attempts  at  washing  gravels  have  been  made  in 
Maine '  and  in  Rhode  Island  in  the  slates  and  gneisses  around 
the  great  intrusions  of  granite,  quartz  veins  are  not  infrequent: 
Traces  of  gold  have  been  met. 

2.13.08.  Example456.  In  the  fundamental  complex  (2.02.17) 
north  of  the  iron  region  at  Ishpeming,  gold  occurs  at  the  Ropes 
mine  in  reticulations  of  pyritous  quartz  and  country  rock  at  the 
contact  of  a  great  intrusion  of  peridotite  with  greenstone  schist. 
Other  less  developed  locations  are  on  quartz  veins  in  the  schists.^ 

2.13.09.  The  Rainy  River  District.  This  includes  the 
country  adjacent  to  Rainy  Lake  and  the  Lake  of  the  Woods. 

*  S.  F.  Emmons,  "  Notes  on  the  Gold  Deposits  of  Montgomery  County, 
Md.,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVIII.,  396,  1890.  See  also  W.  R 
Johnson,  under  Virginia  above,  and  likewise,  Philos.  Mag.,  XXXVI., 
242,  1850,  and  ^mer.  Jour.  Sci.,  ii.,  IX.,  126. 

■^  Eckfeldt,  "Discovery  of  Gold  in  Philadelphia  Clay,"  (Scents  to  cu.  ft.), 
Proc.  Amer.  Phil.  Soc,  VIII.,  278  ;  Amer.  Jour.  Sci.,  ii.,  XXXII.,  297.  C. 
M.  Wetherill,  Note  in  Philos.  Mag.,  IV.,  150,  February,  1853,  and  in  Erd- 
mann's  Jour,  filr  prakt.  Chem. ,  LVIII. ,  447  ;  Amer.  Jour.  Sci. ,  ii. ,  XIX. , 
290. 

^  J.  G.  Pohle  and  John  Torrey,  "Gold  in  Rhinebeck,  Dutchess  County, " 
Amer.  Jour.  Sci.,  ii..  XLVII.,  139.  See  R.  W.  Raymond.  "  The  New  York 
Mining  Law,"  Trans.  Amer.  Inst.  Min.  Eng.,  XVI.,  770. 

*  J.  N.  Blake,  "Gold  at  Dedham,  Mass.,"  Amer.  Jour.  Sci.,  ii.,  II.,  419. 

*  The  subject  is  taken  up  in  the  Report  of  the  Geological  Survey  of  Ver- 
mont, Vol.  II.,  842,  1861,  and  a  map  showing  the  distribution  of  auriferous 
gravels  is  given  in  Plate  I.  O.  P.  Hubbard  refers  to  Gold  in  Vermont  in 
Amer.  Jour.  Sci.,  ii.,  XV.,  147. 

"  Geology  of  New  Hampshire,  III.,  Part  V.,  p.  4,  1878.  H.  Wurtz,  Amer. 
Jour,  of  Mining,  September  12,  1868. 

'  M.  E.  Wadsworth,  "  On  an  Occurrence  of  Gold  in  Maine  "  (in  a  quartz 
vein).  Bull.  Mus.  Comp.  Zool,  VII.,  No.  3,  p.  181,  May,  1881.  Harvard 
Univ.  Bull.,  June,  1881,  p.  219.  Gold  gravels  have  occasioned  some  ex- 
citement on  the  Swift  River.     On  silver  in  Maine,  see  above,  2.09,04. 

®  C.  D.  Lawton,  Rep.  Mich.  Com.  of  Mineral  Statistics,  1887,  p.  167. 
"The  New  Michigan  Gold  Field,"  Eng.  and  Min.  Jour.,  September  22, 
1888,  p.  238.  M.  E.  Wadsworth,  Ann.  Rep.  Mich.  State  Geologist,  issued 
January,  1892,  p.  152. 


384  KEMP'S  ORE  DEPOSITS. 

For  several  years  it  has  been  known  that  gold  prospects  existed 
in  the  region  Ij'ing  along  the  national  boundary,  in  and  north  of 
Minnesota.  Some  claims  in  the  Jlainy  Lake  region  are  in  Min- 
nesota, but  the  greater  part  of  the  productive  or  prospective 
country  lies  in  Ontario.  The  geologj^  of  the  regions  around 
Rainy  Lake  has  been  mapped  in  detail  by  A.  C.  Lawson,  but 
that  around  the  Lake  of  the  Woods  has  not  yet  received  the 
same  complete  study.  Near  Rainy  Lake  the  geology  involves 
Laurent  ian  granites  and  gneisses;  mica  schists  and  finegrained 
micaceous  gneiss  of  the  Coutchiching;  greenish  and  sericitic 
schist,  conglomerate,  graywackes,  etc.,  of  the  Keewatin,  and 
minor  developments  of  eruptives,  such  as  gabbros  and  diabase 
dikes.  The  ore  deposits  embrace  segregated  veins,  fissure  veins 
and  fahlbands,  according  to  H.  V.  Winchell  and  U.  S.  Grant,  as 
cited  below.  The  segregated  veins  are  series  of  overlapping 
lenses  of  auriferous  quartz,  with  pyrite,that,  although  of  no  great 
individual  size,  may  yet  form  a  somewhat  extended  deposit. 
They  occur  in  the  schists  of  the  Coutchiching  and  Keewatin,  and 
run  parallel  to  the  schistosity,  apparently  along  lines  of  local 
faulting.  The  fissure  veins  are  most  pronounced  in  granite. 
They  are  individually  larger  than  the  first  type,  and  when  in 
foliated  rocks,  they  cut  the  schistosity  at  a  greater  or  less  angle. 
The  fahlbands  are  belts  of  foliated  rock  impregnated  with  sul- 
phides. Sulphides  of  iron,  copper,  zinc,  lead,  cobalt  and  silver 
are  known.  The  mines  of  Rainy  Lake  have  not  yet  assumed 
great  economic  importance,  but  are  of  promise.^ 

2.13.10.  The  Lake  of  the  Woods  lies  northwest  from  Rainy 
Lake  and  entirely  within  the  limits  of  Ontario.  The  geologi- 
cal relations  are  much  the  same  as  those  of  the  latter.  Keewatin 
schists  are  infolded  in  Laurentian  granite  and  gneiss,  and  all 

^  A.  P.  Coleman,  "Abstract  of  a  Report  to  the  Bureau  of  Mines  of 
Ontario,'/  Eng.  and  Min  Jour.,  December  22,  1894,  581.  "Clastic  Huron- 
ian  Rocks  of  Western  Ontario,"  Bull.  Geol.  Soc.  Amer.,  IX.,  223,  1898.  A. 
C.  Lawson,  "Report  on  the  Geology  of  the  Rainy  Lake  Region,"  Geol. 
Survey  of  Canada,  Ann.  Rep.,  1887,  Part  F.  W.  H.  Merritt,  "The  Oc- 
currence of  Gold  Ores  in  the  Rainy  Ri vrer  District,  Ontario,"  Trans.  Arner. 
Inst.  Min.  Eng.,  XXVI.,  853,  1896.  W.  W.  Taylor,  "Geology  and  Char- 
acter of  the  Rainy  Lake  Gold  District,"  Eng.  and  Min.  Jour.,  December 
1,  1894,  p.  509.  H.  V.  Winchell  and  U.  S.  Grant,  "  Preliminary  Report  on 
the  Rainy  Lake  Gold  Region,"  Geol.  Survey  of  Minn.,  XXIII.  Ann.  Rep., 
35,  105,  1895. 


GOLD  IN  UNITED  STATES  AND  CANADA.  385 

are  pierced  by  later  granite.  There  is  also  a  very  considerable 
development  of  volcanic  rocks,  both  tuffs  and  flows,  now  more 
or  less  schistose.  Considerable  alteration  has  taken  place  in 
all,  and  as  emphasized  by  W.  H.  Merritt,  secondary  minerals 
have  been  developed.  The  veins  are  found  in  the  schists,  but 
favor  the  portions  near  the  contact  with  the  granite  or  gneiss. 
The  gold  is  free  and  in  the  usual  sulphides,  and  in  some  veins 
there  is  considerable  molybdenite.  Bismuthinite  is  also  re- 
ported. Several  mines  have  reached  a  productive  stage,  and 
there  are  many  prospects.^ 

2.13.11.  In  the  summer  of  1897  indications  of  gold  were 
also  met  in  the  region  near  Michipicoten  River,  which  enters 
Lake  Superior  on  its  northeastern  coast.  Auriferous  quartz 
veins,  some  of  which  have  yielded  good  assays,  have  been 
located.     The  richest  are  near  Wawa  Lake.^ 

ALASKA  AND  THE  CANADIAN  NORTHWEST. 

2. 13. 12.  Geology.  — Our  knowledge  of  the  geology  of  Alaska 
is  still  far  from  complete,  when  the  entire  territory  is  consid- 
ered, but  it  has  been  greatly  amplified  within  the  last  few  years 
by  the  mining  explorations,  and  the  governmental  expeditions 
sent  out  as  a  result  of  them.  The  observations  thus  far  re- 
corded deal  chiefly  with  the  coast,  and  with  the  drainage  basin 
of  the  Yukon,  or  with  the  passes  which  penetrate  to  its  upper 
waters.  Mesozoic  rocks  extend  north  from  Washington  and 
Vancouver  so  as  to  appear  in  Queen  Charlotte's  Island,  and  at 
a  few  points  in  the  Aleutian  Islands.  Tertiary  beds  occur 
over  a  wide  area,  and  have  been  located  at  numerous  points, 
both  on  the  mainland  and  among  the  islands.  Metamorphic 
rocks  from  both  igneous  and  sedimentary  originals,  unaltered 
plutonic  types  and  intruded  dikes,  and  more  recent  effusive  vol- 

^  E.  Coste,  "  Report  on  the  Gold  Mines  of  the  Lake  of  the  Woods,"  Oeol. 
Survey  Canada,  1882-84,  Rep.  K.  W.  Douglass,  ''  The  Lake  of  the  Woods 
District,"  Eng.  and  Min.  Jour.,  February  16,  1895,  p.  152.  W.  H.  Merritt, 
"  The  Occurrence  of  Gold  Ores  in  the  Rainy  River  District,  Ontario," 
Trans.  Amer.  Inst.  Min  Eng.,  XXVI.,  853,  1896.  T.  A.  Rickard,  "The 
Lake  of  the  Woods  Gold  Field,"  Idem,  July  3,  1897,  p.  5.  R.  H.  Williams, 
"The  Lake  of  the  Woods  District,"  Idem,  July  28,  1894,  p.  75. 

^  J.  T.  Donald,  "Canada's  Newest  Gold  Field,"  Eng.  and  Min.  Jour., 
September  25,  1897,  p.  369. 


386 


KEMP'S  ORE  DEPOSITS. 


RECONNAISSANCE   MAP 
OF   A   PORTION   OF   THE 

YUKON  GOLD  BEL.T\ 

AND  ADJACENT  REGIONS  IN  ALASKA 

AND  PART  OF  THE 

NORTHWEST    TERRITORY 

Scale  of  Miles 
0  ao         *| 


60 


1897  /^^3?:V>/^V|^5^^ 

Reproduced  inline-work  after  a  colored  Map/ r?^'"-'  "^:- v^'-'il'-Qy^^^^^ 

by  J.E.  Spurr.    XVIII  Ann.  Rep.         /riIiri^.;J!:f:}^{y^}/j^^^^j^j:-^ 
U.S.  Geological  Sui-vey.    Part  III,  PI.  XXXVra-s^^\'>>;;-'i£^^|^^^J 


PLEISTOCENE 
MOSTLY  LACUSTRINE 

SILTS  NEOCENE 


EOCENE  MISSION  CREEK 

KENAI  SERIES 


TAHKANDIT 
SERIES 


RAMPART 
SERIES 


SECTION  ON  LINE  A-A 


Fig.  150o—  Western  half  of  Geological  map  of  the  Yukon  Gold  Belt  and 
adjacent  regions.     {See  Ym.  \^1.) 


JJATURAL  SCALE 

Fig.  151.— Eastern  Tudfof  OedogicaZ  map  of  the  Yukon  Gold  Belt,  and  ad- 
jacent regions,  reproduced  in  line  work  and  slightly  reduced  from  a 
colored  map  by  J.  E.  Spurr,  XVIIL  Ann.  Rep.  V.  S.  Oeol. 
Survey,  Part  III.,  Plate  XXXV III.,  p.  252. 


388  KEMP'S  ORE  DEPOSITS. 

canics,  some  from  vents  still  active,  are  the  chief  components 
of  the  coastal  exposures. 

In  the  interior,  in  the  Yukon  basin,  and  especially  in 
the  area  near  the  international  boundary,  the  general 
stratigraphy  has  been  more  systematically  studied,  and 
may  now  be  outlined,  since  the  valuable  paper  of  J.  E.  Spurr 
has  become  available.  In  order  to  make  the  geology  of  this 
important  region  clear,  the  colored  reconnaissance  map  of  Spurr 
is  reproduced  in  Figs.  loO  and  151,  in  line  work  on  a  somewhat 
smaller  scale  than  the  original,  and  in  it  the  results  of  his  ex- 
plorations, as  well  as  those  of  Dall,  Hayes,  Geo.  Dawson, 
McConnell  and  others,  are  set  forth. 

The  oldest  formation  is  granite,  of  massive  or  more  rarely 
gneissoid  structure.  It  consists  chiefly  of  quartz,  orthoclase, 
microcline,  plagioclase  and  biotite,  with  accessory  muscovite, 
calcite,  epidote,  garnet,  hematite,  kaolinite,  pyrite  and  chlorite. 
It  is  most  extensively  exposed  south  of  the  Yukon  basin,  but 
outcrops  to  the  north  in  sufficient  amount  to  show  that  the  later 
formations  rest  upon  it.  It  is  considered  Archean,  and  is 
called  the  Basal  Granite.  Immediately  above  it  is  a  series  of 
quartz-schists,  estimated  at  25,000  feet  in  thickness,  and  called 
the  Birch  Creek  series.  Many  quartz  veins  occur  in  it,  chiefly 
parallel  with  the  schistosity.  The  Birch  Creek  series  passes 
into  the  Forty-Mile  series,  which  consists  of  micaceous  and 
hornblendic  schists  with  interbedded  crystalline  limestones. 
The  Forty-Mile  series  likewise  contains  many  quartz  veins,  and 
both  it  and  the  Birch  Creek  series  are  penetrated  by  many 
dikes  of  granite  and  diorite.  In  geologic  succession  the  Ram- 
part series  follows,  and  exhibits  a  heavy  cross-section  and  wide 
areal  distribution  of  diabases,  and  associated  tuffs,  with  some 
impure  limestones  and  shales.  The  Rampart  series  is  probably 
pre- Devonian,  as  is  shown  by  the  fossils  in  the  next  overlying 
series,  and  the  Forty-Mile  and  Birch  Creek  series  are  still 
older,  but  all  are  uncertain  in  their  taxonomic  relations  except 
for  this  approximate  determination.  Quartz  veins  are  also 
present  in  the  Rampart  series.  The  Tahkandit  series  of  white 
and  gray  limestones  with  alternations  of  carbonaceous  shales 
and  conglomerates  follows  next  above.  It  is  known  from  fossils 
to  contain  some  Upper  Carboniferous  beds  and  probably  also 
embraces  others  of  Devonian  iage.     Upon  it  rests  the  Mission 


GOLD  IN  UNITED  STATES  AND  CANADA,  389 

Creek  series  of  black,  calcareous  and  feldspathic  shales  and 
thin  beds  of  impure  limestone,  and  gray  sandstone.  They  are 
known  to  be  Lower  Cretaceous.  The  Kenai  series  succeeds 
with  its  fresh- water  sediments  and  coal  seams  of  Eocene  age. 
Neocene  deposits  follow  and  embrace  the  Nulato  sandstones, 
the  Twelve-mile  beds  of  gravels  and  lignites,  the  Porcupine 
beds  of  sands,  clays  and  conglomerates,  and  the  Palisades  con- 
glomerates with  the  bones  of  huge,  extinct  vertebrates.  The 
Yukon  silts  are  Pleistocene  and  constitute  a  vast  area  of 
abandoned  lake- bottoms  along  the  middle  Yukon.  Eruptive 
basalt  is  also  known,  but  in  connection  with  the  gold,  the  Basal 
granite,  the  Birch  Creek,  Forty-Mile  and  Eampart  series  and 
the  recent  gravels  derived  from  them  are  of  chief  interest. 

In  its  topographic  character  the  interior  is  largely  a  great, 
dissected  plateau  so  far  as  known,  with  rugged  and  uneven 
topography  on  a  minor  scale.  The  ranges  of  mountains 
are  chiefly  developed  near  the  coast.  The  surface  of  the 
interior  plateau  and  the  talus  slopes  are  covered  by  a  heavy 
mantle  of  moss,  called  a  tundra,  whose  roots,  at  a  depth  of  a 
foot  or  two,  are  frozen  in  perpetual  ice.  This  hides  the  geol- 
ogy, and  makes  exploration  difficult  and  fraught  with  great 
hardship.  Along  the  streams  dense  thickets  of  alder  and 
spruce,  and  in  the  glaciated  regions,  the  drift,  all  hide  the 
rocks.  ^ 

'  "Alaska  as  a  Mining  Territory,"  Eng.  and  Min.  Jour.,  June  27,  1885, 
p.  444.  "Mineral  and  Agricultural  Wealth  of  Alaska,"  Eng.  and  Min. 
Jour.,  August  24,  1887,  p.  134.  G.  F.  Becker,  "Reconnaissance  of  the  Gold 
Fields  of  Southern  Alaska,  with  some  Notes  on  General  Geology,"  XVIII. 
Ann.  Rep.  U.  S.  Geol.  Survey,  Part  III.,  p.  7.  Rec.  T.  A.  Blake,  "Re- 
port on  the  Geology  of  Alaska,"  Ex.  Doc,  No.  177,  Fortieth  Congress,  New 
Series,  p.  314,  Washington,  1868.  W.  P.  Blake,  "Geographical  Notes  upon 
Russian- America  and  the  Stickeen  River;"  Report  addressed  to  the  Sec- 
retary of  State,  Washington,  1866.  H.  P.  Gushing,  "Notes  on  the  A  real 
Geology  of  Glacier  Bay,  Alaska,"  Trans.  N.  Y.Acad,  of  Sci.,  XV.,  24. 
"  Notes  on  the  Muir  Glacier  Region  and  its  Geology,"  Amer.  Geol.,  Octo- 
ber, 1891,  207.  W.  H.  Dall,  "Explorations  in  Alaska,"  Amer.  Jour.  Sci., 
ii.,  XLV..  96.  Rec.  "Notes  on  Alaska  and  the  Vicinity  of  Bering 
Straits, "  Ibid. ,  iii. ,  XXI.  104.  "  Notes  on  Alaska  Tertiary  Deposits,  Geologi- 
cal Section  of  the  Shumagin  Islands,"  Ibid.,  iii.,  XXIV.,  67.  "Alaska  and 
its  Resources,"  Washington,  1870.  Rec.  "  Glaciation  in  Alaska,  '  Bull. 
Phil  Soc,  Vol.  VI.,  p.  33,  Washington,  1884.  G.  M.  Dawson,  "Report on 
the  Yukon  District  in  1887,"  Geol.  Survey  of  Canada,  1887-88,  Vol.  III., 
Part  B,  pp.  14B,  17B,  154B-ir)6B.     H.  W  .Elliot,  "Our  Arctic  Provinces," 


390  KEMP'S  ORE  DEPOSITS. 

2.13.13.  Example  38.  (See  above,  2.09.01.)  Douglass 
Island.  A  dike  of  shattered  albite-diorite  (sodium-syenite) 
impregnated  with  gold-bearing  pyrite.  The  largest  and  most 
productive  of  the  mines  along  the  coast  of  Alaska  is  the 
Alaska- Tread  well  and  its  affiliated  properties,  on  Douglass 
Island,  about  two  miles  southeast  from  the  town  of  Jnneau. 
The  ore  body  is  peculiar  and  interesting,  and  while  the  grade 
of  the  ore  is  low,  the  conditions  for  treating  it  cheaply,  and  on 
a  large  scale,  are  very  favorable.  The  geological  relations 
have  recently  been  described  by  G.  F.  Becker,  upon  whose 
paper  the  following  outline  is  based. 

The  country  rock  is  a  carbonaceous  slate  of  uncertain  but 
possible  Triassic  age.  Its  sedimentary  bedding  has  been 
destroyed,  but  its  cleavage  strikes  N.  50  E.,  and  dips  southeast. 
After  the  metamorphism  to  slate,  it  was  penetrated  by  an  irregu- 
lar dike,  which  is  450  feet  and  less  wide,  and  is  considerably  split 
up  by  horses  of  country  rock.     The  dike  rock  is  a  peculiar  one, 

p.  163,  New  York,  1887,  G.  W.  Garside,  "Mineral  Resources  of  Southeast 
Alaska,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXL,  815.  E.  J.  Glave,  "Pioneer 
Pack-horses  in  Alaska, "  The  Century,  September  and  October,  1892.  C. 
W.  Hayes,  "An  Expedition  through  the  Yukon  District,"  Nat.  Geog. 
Mag.,  IV.,  117-162,  1892.  Angelo  Heilprin,  "Alaska  and  the  Klon- 
dike,"  New  York,  1899.  R.  G.  McConnell,  "Glacial  Features  of  Parts  of 
the  Yukon  and  Mackenzie  Basins,"  Geol.  Soc.  of  Amer.,  I.,  p.  540.  H.  F. 
Reid,  "Glacier  Bay  and  its  Glaciers,"  XVI.  Ann.  Rep.  Dir.  U.  S.  Geol. 
Survey,  1896,  I.,  421.  I.  C.  Russell,  "The  Surface  Geology  of  Alaska," 
Geol.  Soc.  of  Amer.,  I.,  p.  99.  "An  Expedition  to  Mt.  St.  Elias,  Alaska," 
Nat.  Geogr.  Mag.,  III.,  53,  204,  1891.  "Mt.  St.  Elias  and  its  Glaciers," 
Amer.  Jour.  Set.,  March,  1892,  169.  "Origin  of  the  Gravel  Deposits  be- 
neath the  Muir  Glacier,  Alaska,"  Amer.  Geol,  March,  1892,  180.  J.  E. 
Spurr  and  H.  B  Goodrich,  "Geology  of  the  Yukon  Gold  District,"  XVIII. 
Ann.  Rep.  U.  S.  Geol.  Survey,  Part  III.,  87.  Rec.  E.  R.  Skidmore, 
"Alaska,"  Rep.  Director  of  the  Mint,  1883,  p.  17,  and  1884,  p.  17.  J.  Stan- 
ley-Brown, "Auriferous  Sands  at  Yakutat  Bay,  Alaska,"  Nat.  Geogr.  Mag., 
Vol.  III.,  196, 1891.  J.  J.  Stevenson,  "Some  Notes  on  Southeastern  Alaska 
and  its  People,"  Scottish  Geogr.  Mag.,  February,  1893.  J.  B.  Tyrrell, 
"Glacial  Phenomena  in  the  Canadian  Yukon  District,"  Bull.  Geol.  Soc. 
Amer.,  X.,  193,  1899.  G.  H.  Willianis,  "Notes  on  Some  Eruptive  Rocks 
from  Alaska,"  Nat.  Geogr.  Mag.,  IV.,  63, 

Note. — The  Bulletin  of  the  Boston  Public  Library  for  September,  1897, 
p.  153,  has  a  complete  bibliography  of  the  Yukon  region  up  to  that  date. 
In  1899,  the  U.  S.  Geological  Survey  issued  a  pamphlet  entitled,  "Maps 
and  Descriptions  of  Routes  of  Exploration  in  Alaska,"  together  with  a 
valuable  series  of  maps. 


GOLD  IN  UNITED  STATES  AND  CANADA.  391 

and  is,  as  a  rule,  now  much  altered,  but  in  tbe  freshest  material 
available,  it  is  almost  entirely  albite.  It  contains  small 
amounts  of  augite,  born  blende,  biotite  and  a  few  plagioclases 
other  than  albite.  Secondary  quartz  is  abundant.  After  the 
intrusion  of  tbe  diorite,  a  gabbro  dike,  with  some  tendencies 
toward  diabase  in  its  texture,  penetrated  along  the  northeast  side 
of  the  diorite,  being  sometimes  entirely  in  the  slate.  The 
gabbro  is  chiefly  augite  and  plagioclase,  and  carries  no  value 
in  gold  that  is  practically  serious.  After  the  intrusion  of  the 
gabbro  a  narrow  dike  of  analcite-  basalt  4  to  6  feet  wide  cut  all  the 
other  rocks.  Before  its  intrusion,  the  others,  and  especially  the 
albite-diorite,  suffered  severely  from  crushing,  the  latter  being 
cracked  by  series  of  planes  at  right  angles  with  each  other,  and 
inclined  at  45°  to  the  horizon.  Along  these  cracks  the 
mineralization  has  taken  place,  and  quartz,  calcite,  gold-bearing 
pyrite,  with  rare  chalcopyrite,  mispickel,  blende  and  galena 
entered.  The  analcite-basalt  accompanied  or  closely  followed 
the  mineralization.  During  the  latter  the  ferromagnesian  sili- 
cates of  the  original  albite-diorite  were  replaced  by  the  pyrite.^ 

F.  D.  Adams  has  detected  metallic  gold  in  the  midst  of  the 
pyrite  in  a  thin  section  of  the  ore. 

South  from  the  Tread  well  mine  is  an  un  worked  claim,  and 
then  toe  Mexican,  which  is  operated  by  the  same  parties  as  the 
Tread  well. 

In  connection  with  the  petrography  of  the  Tread  well  ore,  it 
is  interesting  to  remark  that  numerous  dikes  of  albitic  rock 
occur  in  the  Sierras  of  California,  and  are  known  to  be  gold- 
bearing  in  a  number  of  instances.^ 

2. 13. 14.  The  other  mines  that  have  been  developed  along  the 
coastal  region  are  not  numerous  as  yet.  Some  three  miles  east 
of  Juneau  there  is,  in  the  midst  of  the  mountains,  a  small 
abandoned  lake  basin  called  Silver  Bow  basin,  whose  sands  are 

*  F.  D.  Adams,  ' '  On  the  Microscopical  Character  of  the  Ore  of  the 
Treadwell Mine,  Alaska,"  Amer.  Geol,  August,  1889,  p.  88.  G.  F.  Becker, 
"  Reconnaissance  of  the  Gold  Fields  of  Southern  Alaska,  with  some  Notes 
on  the  General  Geology,"  XVIII  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey,  Part 
III.,  p.  1.  Rec.  G.  M.  Dawson,  "  Notes  on  the  Ore  Deposits  of  the  Tread- 
well  Mine,  Alaska,"  Amer.  Geol.,  August,  1889,  p.  84.  Min.  and  Set. 
Press,  San  Francisco,  September  27,  October*4,  1884. 

'  SeeH.  W.  Turner,  "  Replacement  Ore  Deposits  in  the  Sierras,"  Jour,  of 
<3eol.,  May-June,  1899,  389.     Compare  also  paragraph  2.12.20. 


392 


KEMP'S  ORE  DEPOSITS. 


gold-bearing  to  a  degree  that  admits  of  profitable  hydraulickiDg. 
In  the  surrounding  mountains  of  schists  there  are  a  few  veins 
that  have  received  attention  at  the  Bennet,  the  Lane  and  Hay- 
ward  and  the  Taku  mines.  Over  the  divide  to  the  south,  in 
the  drainage  of  Sheep  Creek  basin,  are  several  other  veins  in 
schists.  They  carry  silver-bearing  sulphides,  with  minor  gold 
values.  The  country  rock  is  schist,  carbonaceous  and  mica- 
ceous, with  gabbro  dikes. 

2.13.15.     At  Sumdum  Bay  there  are  slates,  which  are  pene- 
trated by  granitic  dikes.     They  also  contain  lenses  of  quartz 


Fig.  153. — Map  of  the  Juneau  mining  district,  southeast  Alaska.     After 

O.  F.  Becker,  XVIII.  Ann.  Rep.  Dir.  U.  S.  Oeol.  Survey, 

Part  III.,  Plate  XVI,  reduced. 


with  sulphides  carrying  gold  and  silver.  Near  Berner's  Bay 
the  diorite  has  quartz  veins  with  sulphides,  and  at  Funter's 
Bay,  in  the  Admiralty  Islands,  schists  derived  from  diabase 
hold  veins  in  cross-fissures.  Pyrite  and  pyrrhotite  occur  in 
a  gangue  of  quartz.  Near  Sitka  veins  with  low  grade  ores 
have  been  found  in  a  pyroclastic  diorite,  and  on  Kadiak 
Island  there  are  some  prospects,  as  well  as  gold-bearing  beach 
sands.  Next,  however,  after  the  mines  on  Douglass  Island,  the 
largest  on  the  Alaskan   coast  is  the   Apollo  mine  on  Unga 


GOLD  IN  UNITED  STATES  AND  CANADA,  39;i 

Island.  The  wall  rock  is  andesite,  probably  post- Miocene. 
The  ores  are  free  gold,  pyrite,  galena,  zincblende,  chalcopyrite, 
and  some  native  copper,  in  a  large  chute  along  a  zone  of  frac- 
ture. 

2.13.16.  The  Yukon  Basin.  The  greatest  interest,  so  far  as 
the  mineral  resources  of  Alaska  and  the  Northwest  Territory  of 
Canada  are  concerned,  centers  around  the  gold  placers  of  the 
Yukon  basin.  So  far  as  yet  developed  the  richest  lie  in  Cana- 
dian territory,  and  from  these  the  chief  production  has  thus  far 
been  obtained,  but  the  older  workings  are  on  the  American 
side,  and  some  gold  is  annually  obtained  from  them  yet.  The 
gold  occurs  in  two  different  kinds  of  gravels.  The  ore  lies  on 
the  bed-rock  beneath  the  courses  of  the  smaller  streams  and 
their  tributary  gulches,  which  latter  are  locally  called  ^'pups." 
Above  the  pay-streak  lies  a  variable  thickness  of  barren,  frozen 
gravel,  which  is  overlain  by  peaty  muck.  The  pay-streak  is 
exposed  by  thawing  out  a  pit  in  the  frozen  gravel  by  means  of 
fires  and  heated  stones,  so  that  it  can  be  excavated  and  stacked 
up  until  the  warm  season  affords  water  for  panning,  cradling, 
or  more  rarely,  sluicing.  Except  that  the  ground  is  frozen  the 
placers  do  not  differ  from  those  already  fully  outlined. 

2.13.17.  The  second  variety  of  gravels  is  the  "bench" 
gravel,  which  occurs  on  the  sides  of  the  valleys  above  the  pres- 
ent stream  bottoms.  They  are  regarded  b}^  Tyrrell  as  the 
terminal  moraines  of  small  glaciers,  which  came  but  a  compar- 
atively short  distance  down  the  hillsides  and  stopped. 

2.13.18.  ^he  source  of  the  gold  appears  to  have  been  the 
quartz  veins  in  the  Birch  Creek,  Forty-Mile  and  Rampart 
series,  as  described  under  paragraph  2.13.12.  The  veins  seem 
to  have  been  individually  small,  for  thus  far  no  one  has  yet 
proved  available  for  deep  mining.  A  few  have  been  proved  to 
actually  contain  gold,  and  have  thus  given  real  as  well  as 
theoretical  ground  for  the  above  inference.  The  veins  chiefly 
run  parallel  with  the  foliation,  although  some  fissure  veins,  that 
cross  it,  are  known.  Assays,  so  far  as  recorded,  while  they 
demonstrate  the  presence  of  gold,  do  not  indicate  great  richness. 
(Citations  of  the  literature  will  be  found  under  2.13.12.) 

2.13.19.  South  of  the  headwaters  of  the  Yukon,  and  after 
an  interval  of  barren  territory,  so  far  as  known,  lies  the  Cassiar 
district,  which  is  reached  from  the  coast  via  Wrangell  and 


394  KEMP'S  ORE  DEPOSITS. 

the  StickeeD  River.  From  the  coast  inland  schistose  rocks, 
with  a  few  limestones  and  extensive  intrusions  of  granite  form 
the  oldest  rocks,  but  there  are  many  sheets  of  basalt  of  most 
interesting  character,  especially  near  the  head  of  navigation  on 
the  Stickeen  River.  The  chief  gold  discoveries  have  been 
made  in  the  past  in  the  drainage  area  of  Dease  Lake.  The 
gold  occurred  in  stream  gravels,  but  the  heavy  glacial  deposits 
have  at  times  buried  them  under  a  great  amount  of  later  and 
barren  debris.  One  of  the  routes  to  the  Klondike  passes 
through  the  region.^ 

2.13.20.  In  the  drainage  area  of  the  Columbia  River  just 
north  of  the  international  boundary,  and  lying  between  it  and 
the  line  of  the  Canadian  Pacific  railway,  important  develop- 
ments in  mining  have  been  made  in  recent  years.  The  region 
is  mountainous  and  rugged.  The  Columbia  and  its  tributary, 
the  Kootenay,  into  v^rhich  flow^s  the  Slocan,  have  their  courses 
largely  formed  by  long  and  relatively  narrow  lakes,  which, 
being  navigable,  have  greatly  aided  in  the  development  of  the 
mines.  The  Columbia  passes  through  Upper  and  Lower  Arrow 
Lake;  the  Slocan  heads  in  Slocan  Lake,  lying  to  the  east;  and 
the  Kootenay  drains  the  waters  of  Kootenay  Lake  still  further 
east.  All  these  lie  in  long  north  and  south  valleys,  and  into 
them  the  smaller  streams  discharge  from  the  mountains  lying 
east  and  west.  In  the  valleys,  and  on  the  mountain  slopes 
along  these  creeks  the  veins  have  been  located.  The  Slocan 
district  extends  from  west  of  Lower  Arrow  Lake  eastward  be- 
yond Slocan  Lake;  the  Ainsworth  district  surrounds  Kootenay 
Lake;  the  Nelson  lies  along  the  Kootenay  River  between 
Kootenay  Lake  and  the  Columbia  River;  while  Trail  Creek 
embraces  both  banks  of  the  Columbia  as  it  leaves  Canada  and 
crosses  the  international  boundary. 

Dr.  Geo.  M.  Dawson^  recognizes  on  Kootenay  Lake  and  on 
Adams  Lake  (which  latter  is  150  miles  northward  of  the 
former)  the  following  series,  beginning  with  the  oldest 
{Bull.  Geol.  Soc.  Amer.  IL,  1C8): 

'  G.  M.  Dawson,  Oeol.  Survey  of  Canada,  III.,  1888,  Report  B.  E.  D. 
Self,  "TheCassiar  District,"  Eng.  and  Min.  Jour.,  February  18, 1899,  205. 

"^  G.  M.  Dawson,  "Report  on  a  Portion  of  the  West  Kootenay  District, 
British  Columbia,"  Rep.  B.  Can.  Geol.  Survey,  IV.,  1888-89.  Rec.  "Note 
on  the  Geological  Structure  of  the  Selkirk  Range,"  Bull.  Geol.  Soc.  Amer., 
II.,  165,  1891. 


GOLD  IN  UNITED  STATES  AND  CANADA.  395 

1.  The  Shuswap  series.  Mica  schists,  gneisses  and  marbles. 
Archean. 

2.  The  Nisconlith  series.  Black  shaly  or  schistose  argillite, 
with  some  limestone.     Cambrian. 

3.  The  Adams  Lake  series.  Gray  and  greenish  schists. 
Cambrian  and  Silurian. 

Above  these  are  limestones,  argillites  and  schists. 
W.  A.  Carlyle,^  in  the  report  cited   below,   mentions  above 
the  Nisconlith  series  in  the  Kootenay  region. 

3.  The  Kaslo  schists,  comprising  a  series  of  greenish,  proba- 
bly diabasic  schistaj;^nterbedded  with  some  slates  or  dark  argil- 
lites, and  limestones. 

4.  The  Slocan  slates,  a  series  of  dark  shales  and  slates,  with 
limestones  and  calcareous  quartzites.  {Bulletin  Bureau  of 
Mines,  p.  45.) 

In  addition  to  the  stratified  rocks  there  are  vast  intrusions  of 
granite  regarded  as  later,  and  also  many,  more  basic  rocks,  such 
as  porphyrite,  diabase  and  gabbro,  which  are  often  intimately 
associated  with  the  ore  bodies. 

2.13.21.  In  the  Slocan  district,  W.  A.  Carlyle  has  recognized 
four  kinds  of  veins,  according  to  the  variety  of  ores  furnished, 
viz. :  (1)  Those  with  argentiferous  galena,  blende  and  some 
tetrahedrite  in  a  gangue  of  quartz  and  siderite.  They  cut  strati- 
fied rocks,  dikes  and  granite  in  one  place  and  another.  Gold 
values  are  known  but  are  not  of  great  moment.  These  veins 
are  the  chief  ones  of  the  region.  (2)  Veins  of  argentiferous 
tetrahedrite,  jamesonite  and  silver  minerals  in  quartz  gangue  in 
granite  and  stratified  rocks,  but  not  numerous.  (3)  Veins  in 
granite  with  quartz  gangue,  carrying  argentite,  native  silver 
and  gold.  (4)  Gold  quartz  veins  in  granite.  {Bulletin  III.,  yi^, 
46-48.)  In  the  Ainsworth  district  all  the  geological  series  are 
met,  and  any  one  may  be  the  wall  rock  of  a  vein.  The  com- 
mon gangue-minerals  are  quartz  and  calcite,  and  the  ores  are 
silver-bearing  galena,  with  some  blende;  or  pyrites;  or  silver 
minerals  with  more  or  less  of  the  other  sulphides,  or  of  tetrahe- 
drite with  them.     In  the  Nelson  district  the  rocks  and  the  ores 

'  Wm.  A.  Carlyle,  "Report  on  Slocan,  Nelson  and  Ainsworth  Mining 
Districts  in  West  Kootenay,  British  Columbia,"  Bull.  J II.,  Bureau  of 
Mines,  Victoria,  B.  C,  1897.  Annual  reports,  with  maps,  are  issued  by 
the  Provincial  Mineralogist,  Victoria,  B.  C. 


396  KEMP'S  ORE  DEPOSITS. 

are  somewhat  different  from  those  previously  described,  and 
tend  to  resemble  the  ones  mined  at  Trail  Creek.  The  country 
rocks  are  porphy rites,  gabbros,  diabases  and  slates,  cut  by 
numerous  dikes.  The  ores  are  silver-bearing  sulphides  of  cop- 
per, especially  chalcopyrite,  and  the  common  associate  of  the 
latter  in  rocks  of  this  character,  pyrrhotite.  Gold  is  very  sub- 
ordinate.^ In  the  Trail  Creek  district  igneous  rocks  are  the 
chief  varieties  present.  There  is  an  older  series,  according  to 
R.  G.  McConnell,^  of  porphyrites,  diabases,  gabbros,  tuffs,  and 
agglomerates,  with  occasional  patches  of  limestone,  which  afford 
some  fosSils  of  probable  Carboniferous  affinities,  and  with  some 
inclusions  in  the  igneous  rocks  of  black  slJfe.  Later  than  this 
igneous  series,  is  granite,  and  through  both,  dikes  of  both 
acidic  and  basic  rocks  have  been  intruded.  The  chief  economic 
interest  centers  about  a  small  area  of  gabbro,  near  the  town  of 
Rossland,  and  about  four  miles  long  by  one  mile  wide.  From  a 
gabbroof  granitoid  texture  in  the  central  mass,  it  passes  grad- 
ually into  a  rimof  augite-  and  uralite- porphyrites  and  diabase, 
which  are  seldom  over  a  mile  across,  and  which  are  brecciated. 
At  or  near  the  contact  of  the  gabbro  and  the  porphy ri tic  border, 
are  met  the  ore  bodies.  The  ores  consist  of  auriferous  and 
slightly  argentiferous  pjrrhotite  and  chalcopyrite.  They  are 
not  of  high  grade  as  a  rule,  the  gold  ranging  from  a  trace  to 
several  ounces,  and  the  silver  from  a  trace  to  four  or  five 
ounces.  A  little  nickel  and  still  less  cobalt  can  also  be  de- 
tected. Other  minerals  are  not  prominent;  molybdenite,  high- 
ly auriferous,  and  rarely  galena  and  blende  have  been  recorded. 
The  oxidized  zone  extends  but  a  few  feet  below  the  surface. 
It  is  still  somewhat  of  a  mooted  point  among  observers,  as  to 
whether  they  are  direct  crystallizations  from  the  cooling 
magma;  or  secondary  segregations  from  the  enclosing  basic 
walls;  or  replacements  along  lines  of  Assuring;  or  true  fissure 
veins.  One  mine  and  another  seem  to  give  support  to  each  of 
these  views. 

The  geological  relations  strongly  suggest  those  of  Sudbury, 
later  described  under  nickel,  and  also  those  of  many  nickel 

'  The  details  of  these  districts  are  taken  from  the  Bulletin  of  W.  A. 
Carlyle,  previously  cited. 

"^  R.  G.  McConnell,  '*  Preliminary  Abstract, "  issued  in  Rossland  Weekly 
Mining,  March  18,  1897,  a  local  paper. 


OOLD  IN  UNITED  STATES  AND  CANADA.  397 

Tegions  in  Norway  and  elsewhere  in  the  world.  The  question 
of  their  direct  origin  from  a  fused  and  cooling  magma,  is  an 
important  and  interesting  one,  and  examination  should  be  care- 
fully directed  toward  its  solution.  From  observations  made  in 
connection  with  recent  litigation  over  the  War  Eagle  claim, 
W.  Lindgren  reached  the  conclusion  that  the  ores  had  certainly 
been  deposited  by  replacement. 

2.13.22.  Example  45c.  Nova  Scotia.  The  southeastern 
portion  of  Nova  Scotia,  exclusive  of  Cape  Breton  Island,  is 
chiefly  composed  of  a  vast  series  of  metamorphosed,  fragmenfcal 
deposits,  which  in  places  contain  gold-bearing  quartz  veins  of 
very  interesting  geological  relations.  As  a  rule,  the  veins  con- 
form to  the  bedding  of  the  wall-rocks  and  therefore  present 
structural  problems,  exactly  like  those  of  thin  beds  in  a  folded 
and,  to  some  extent,  faulted  sedimentary  series.  The  age  of 
the  sediments  is  thought  by  some. to  be  Cambrian,  by  others 
pre-Cambrian  or  Algonkian,  the  absence  of  assured  fossils 
making  the  question  an  open  one.  The  metamorphic  rocks 
are  penetrated  by  numerous,  great  intrusions  of  granite,  which 
constitute  no  inconsiderable  part  of  the  6,000  or  7,000  square 
miles  that  the  area  embraces.  The  strata  have  been  divided 
by  geologists  into.two  series.  The  upper,  approximatelj'  3,000 
feet  thick,  consists  of  dark,  pyritous  slates,'  with  some  beds  of 
quartzite,  but  with  few  veins.  The  lower  series,  roundly 
estimated  at  8,000  feet,  has  a  much  larger  proportion  of  coarse 
sediments  and  em  braces  slates,  quartzites,  sandstones,  and  even 
conglomerates.  A  Lower  Carboniferous  conglomerate  is  known 
to  overlie  the  metamorphics,  and  to  contain  boulders  of  the  gold- 
V)earing  quartz  veins,  so  that  the  mineralization  certainly  was 
of  earlier  date.  The  slates,  and  even  the  quartzites,  are  quite 
richly  provided  with  pyrites,  and  are  known  to  carry  gold  even 
at  a  distance  from  the  veins.  There  is  reason  to  think  that 
this  gold  was  deposited  with  them  originally,  and  even  the 
pyrite  may  be  of  metamorphic  production,  from  materials  laid 
down  in  the  sediments.  The  presence  of  the  gold  and  pyrites 
in  the  slates  has  an  important  bearing  on  the  methods  of 
enrichment  of  the  veins  and  the  direction  taken  by  the  gold- 
bearing  solutions. 

Inasmuch  as  the  larger  veins  lie  parallel  with  the  bedding 
-and  conform  to  the  folds  of  the  sediments,  it  is  evident  that  the 


GOLD  IN  UNITED  STATES  AND  CANADA.  399 

quartz  was  deposited  in  them  before  the  folding  took  place.  J. 
E.  Woodman  states  that  the  original  filling  of  the  veins,  pre- 
sumably by  uprising  solutions,  was  not  accompanied  by  the  in- 
troduction of  much  gold.  This  came  later,  during  the  meta- 
morphism,  and  probably  was  contributed  by  the  pyritous  wall- 
rock.  The  first  and  major  folds  w^ere  developed  with  axes 
running  approximately  east  and  west.  In  time  a  second 
compression  nearly  at  right  angles  to  the  first,  threw  these  folds 
into  a  north  and  south  series,  and  caused  many  faults,  mostly 
reversed.  The  corrugations  produced  in  the  first  series  of  folds 
by  these  later  ones,  gave  rise  to  the  so-called  "barrel  quartz," 
and  as  the  latter  has  the  reputation  of  carrying  good  values  in 
gold,  there  may  have  been  some  additional  enrichment  of  it 
during  the  later  disturbances.  Probably  the  intrusion  of  the 
granite  followed  the  second  folding,  but  it  is  not  certain  that  it 
may  not  have  preceded  the  first  upheavals.  The  second 
period  of  disturbance  produced  some  fissures,  which  were  filled 
at  Cow  Bay  with  gold  quartz.  In  the  subsequent  history  of 
the  series,  a  pronounced  northeastern  cleavage  was  developed, 
and  some  small  faulting.  Erosion  has  been  severe,  and  has 
planed  off  the  domes  produced  by  the  cross-folding,  and  has 
largely  determined  the  location  and  extent  of  the  mining  dis- 
tricts. 

While  the  bedded  character  of  the  larger  veins  has  been 
emphasized,  it  must  be  appreciated  that  they  throw  off  stringers 
into  the  walls,  called  "angulars,"  and  that  parallel  ones  are 
connected  by  cross-veins.  Still,  except  at  Cow  Bay,  fissure 
veins  of  the  ordinary  type  are  not  often  met. 

The  ore  minerals  of  the  veins  are  free  gold,  gold- bearing 
pyrite,  mispickel,  and  rarely  galena  and  blende.  The  gangue 
is  chiefly  quartz,  but  calcite  occurs  sporadically.  The  veins 
average  less  than  a  foot  in  width,  but  may  be  several  feet  as  an 
exception.  They  favor  horizons  where  a  soft  rock,  usually  slate, 
lies  near  a  hard  one,  usually  quartzite.^ 

'  In  the  following  bibliography  the  citations  given  in  the  previous  edi- 
tions are  greatly  expanded  by  the  aid  of  Bulletin  127  of  the  U.  S.  Geo- 
logical Survey  and  the  very  complete  list  in  the  paper  of  J.  E.  Woodman. 
W.  J.  Anderson,  "  Gold  Fields  of  Nova  Scotia, "  Trans.  Lit.  and  Hist.  Soc, 
of  Quebec,  Part  II.,  pp.  35-56,  1864.  L.  W.  Bailey,  "  Prehminary  Report  on 
Southwestern  Nova  Scotia,"  Oeol.  Survey  ('anada,  1892-93,  Report  Q. 
G.  F.  Becker,  "Gold  Fields  of  the  Southern  Appalachians,"  XVL  Ann 


400  KEMP'S  ORE  DEPOSITS, 

2.13.23.  Gold  elsewhere  in  Canada.  Auriferous  gravels 
have  been  located  at  the  headwaters  of 'the  Chaudiere  River,  in 
eastern  Quebec,  and  some  quartz  veins  are  found  in  the  meta- 
morphic  rocks  of  the  same  region.     They  have  been  worked  to 

Rep.  U.  S.  Geol.  Survey,  III.,  330.  J.  S.  Campbell,  "Report  on  the  Gold 
Fields,  Eastern  Section,"  Halifax,  1862;  "Report  on  the  Gold  Fields," 
Halifax,  1863.  J.  W.  Dawson,  "On  Recent  Discoveries  of  Gold  in  Nova 
Scotia,"  Can.  Nat.  and  Geol,  VI.,  417,  1861.  The  various  editions  of 
"Acadian  Geology,"  of  which  the  third,  London,  is  the  latest,  1878.  E. 
R.  Faribault,  "Report  on  the  Lower  Cambrian  Rocks  of  Guysborough 
and  Halifax  Counties,"  Geol.  Survey  Canada,  1886,  Report  P,  129.  H. 
Fletcher,  "  Report  on  Various  Counties  in  Nova  Scotia."  Idem,  1886,  Report 
P,  1-129.  E.  Gilpin,  "The  Gold  Fields  of  Nova  Scotia,"  Eng.  and  Min. 
Jour.,  XXXIV.,  5,17,1882.  "  Results  of  Past  Experience  in  Gold  Mining 
in  Nova  Scotia,"  Brit.  Assoc.  Adv.  Sci.,  LIII.,  711,  1885.  "Nova  Scotia 
Gold  Mines,"  Trans.  Amer.  Inst  Min.  Eng.,  XIV.,  674,  1886.  Rec. 
"Notes  on  Nova  Scotia  Gold  Fields,"  Trans.  Roy.  Soc.  Can.,  VII.,  63, 
1888.  "The  Evidence  of  a  Nova  Scotia  Carboniferous  Conglomerate," 
Idem,  VIII.,  117,  1890.  "Ores  of  Nova  Scotia,"  Halifax,  1898.  W. 
Gossip,  "The  Rocks  in  the  Vicinity  of  Halifax,'  Proc.  and  Trans.  Nova 
Scotian  Inst.  Nat.  Sci.,  I.,  Part  II.,  44,  1864.  "On  the  Barrel  Quartz  of 
Waverly,"  Idem,  L,  Part  III.,  141,  1865.  P.  S.  Hamilton,  "Auriferous 
Deposits  of  Nova  Scotia,"  Idem,  I.,  Part  IV.,  43,  1866.  C.  F.  Hartt,  "Pre 
Carboniferous  Gold,"  Can.  Nat.,  New  Series,  I.,  459,  1864.  A.  Heathing 
ton,  "Guide  to  the  Gold  Fields  of  Nova  Scotia,"  1868.  H.  Y.  Hind, 
"Report  on  the  Waverly  Gold  District,"  Halifax,  1869.  "Gold  Deposits  of 
Nova  Scotia,"  Can.  Nat,  New  Series,  IV.,  229,  1869.  "Notes  on  the 
Structure  of  the  Nova  Scotia  Gold  Districts,  "Proc.  and  Trans.  Nova  Scotian 
Inst.  Nat.  Sci.,  II.,  Part  III.,  102.  "Preliminary  Report  on  a  Gneissoid 
Series  Underlying  the  Gold-bearing  Rocks,"  etc.,  Halifax,  1870.  See  also 
Quar.  Jour.  Geol  Soc,  XXVI.,  468,  1870,  and  Amer.  Jour.  Sci.,  XL., 
347,  1870.  "Report  on  the  Sherbrook  Gold  District,"  etc.,  Halifax.  1870. 
"Report  on  the  Mount  Uniacke,  Oldham,  and  Renfrew  Gold  Mining  Dis 
tricts,"  Halifax,  1872.  D.  Honeyman.  "  On  the  Geology  of  the  Gold  Fields 
of  Nova  Scotia,"  Quar.  Jour.  Geol.  Soc,  XVIII.,  342,  1862.  "Geology  of 
the  Gay's  River  Gold  Field,  "Proc.  and  Trans.  Nova  Scotian  Inst.  Nat.  Set.. 
II.,  76,  1870.  H.  How,  "Mineralogy  of  Nova  Scotia,"  1868,  and  again  in 
official  report,  Halifax,  1869.  J.  Howe,  "Report  on  the  Gold  Fields." 
Halifax,  1860.  "Tangier  Mines,"  report  to  the  Provincial  Secretary,  Hali- 
fax, 1860.  "Nova  Scotia  Gold  Fields,"  Halifax,  1861.  " Report  on  Gold 
Fields,"  1871.  T.  S.  Hunt,  "Report  on  the  Gold  Regions  of  Nova  Scotia," 
Geol.  Survey  Can.,  1868;  Can.  Nat,  February,  1868.  W.  E.  Logan,  Geol 
Survey  of  Can.,  1863,  and  atlas,  1865.  "Notes  on  the  Gold  of  Eastern 
Canada,'  Montreal,  1864.  J.  Marcou  and  C.  T.  Jackson,  "Note  on  Gold 
Slates  of  Nova  Scotia,"  Proc  Post.  Soc  Nat  Hist.,  IX.,  47,  1862.  O.  C. 
Marsh,  "The Gold  of  Nova  Scotia,"  Amer.  Jour.  Sci.,  XXXII.,  395,  1861. 


OOLD  IN  UNITED  STATES  AND  CANADA.  40! 

a  small  extent.^  Auriferous  mispickel  has  beeu  developed  in 
considerable  quantity  at  Marmora  (or  Deloro),  Hastings 
Count5%  Ontario.  It  occurs  with  quartz  in  a  vein  of  complex 
geological  relations,  and  after  proving  refractory  to  older 
methods  of  treatment,  has  yielded  to  the  cyanide  process.^ 
Kegarding  the  mineral  resources  of  the  Hudson  Bay  terri- 
tory, some  further  notes  have  been  recorded  by  Dr.  Robert 
Bell.' 

2.13.24.  The  following  table  gives  an  idea  of  the  relative 
importance  of  the  several  States.  Full  details  of  the  United 
States  and  other  countries  are  given  in  the  Annual  Reports  of 
the  Director  of  the  Mint,  the  Mineral  Resources  of  the  United 
States  Geological  Survey,  and  the  Mineral  Industry^  the 
annual  statistical  number  of  the  Engineering  and  Mining 
Journal. 

A.  Michel  and  T.  S.  Hunt,  "Report  on  the  Gold  Region  of  Canada," 
Can.  Oeol.  Survey,  1866,  49-90.  G.  F.  Monckton,  "  The  Auriferous  Series 
of  Nova  Scotia,"  Proc.  Oeol.  Assoc,  XI.,  454,  1891,  London.  H.  F.  Perley, 
"Gold  in  Nova  Scotia,"  Can.  Nat.,  II.,  198,  1865.  H.  Poole,  "Report  on 
Gold  Fields,  Western  Section,"  Halifax,  186^.  "The  Gold  Leads  of  Nova 
Scotia,"  Quar.  Jour.  Geol.  Soc,  XXXVI.,  307,  1880.  W.  H.  Prest,  "Deep 
Mining  in  Nova  Scotia,"  Proc.  and  Trans.  Nova  Scotian  Inst.  Nat.  Set., 
VIII.,  420,  1895.  A.  R.  C.  Selwyn,  "Gold  Fields  of  Quebec  and  Nova 
Scotia,"  Can.  Geol.  Survey,  1870-71,  pp.  252-289.  B.  Silliman,  Jr.,  "On 
the  so-called  Barrel  Quartz  of  Nova  Scotia,"  Amer.  Jour.  Sci.,  XXXVIII., 
104,  1864.  'Report  on  the  Lake  Loon  Gold  Mining  Co.,"  1864.  "Report 
on  the  New  York  and  Nova  Scotia  Gold  Mining  Co.,"  1864.  B.  Symons, 
"The  Gold  Fields  of  Nova  Scotia,"  Trans.  Min.  Assoc,  and  Inst.  Cornwall, 
III.,  80,  1892.  J.  E.  Woodman,  "Studies  in  the  Gold-bearing  Slates  of 
Nova  Scotia,"  Proc.  Post.  Soc.  of  Nat.  Hist,  XXVIII.,  375,  1899.  Rec. 
There  are  also  several  official  reports  to  provincial  officers  of  Nova 
Scotia's  Department  of  Mines. 

*  R.  W.  Ellis,  "  Report  on  the  Mineral  Resources  of  Quebec,"  Oeol.  Sur- 
vey of  Can.,  New  Series,  1888-89,  Report  K.  Trans.  Amer.  Inst.  Min, 
Eng.,  XVIII,  316.  A.  Michel  and  T.  S.  Hunt,  "Report  on  the  Gold  Re- 
gions of  Canada,"  Oeol.  Survey  of  Can.,  1866,  49-90. 

"^  "  The  Marmora  Gold  Mine,"  Eng.  and  Min.  Jour.,  October  23,  1880,  p. 
266.  T.  S.  Hunt,  "  Report  on  the  Gold  Region  of  Hastings,"  Oeol.  Survey 
of  Can.,  Montreal,  1867.  R.  P.  Rothwell,  "The  Gold  bearing  Mispickel 
Vein  of  Marmora,  Ontario,"  Trans.  Amer.  Inst.  Min.  Eng.,  IX.,  p. 
409. 

'  R.  Bell,  "Mineral  Resources  of  the  Hudson  Bay  Territories,"  Trans. 
Amer.  Inst.  Min  Eng.,  XIV.,  690,  1886.  See  also  Trans.  Roy.  Soc.  Can., 
II..  241.1885. 


i02 


KEMP'S  ORE  DEPOSITS. 


Alaska , 

Arizona 

California , 

Colorado 

Georgia 

Idaho , 

Michigan , 

Montana 

Nevada  

New  Mexico 

North  Carolina, 

Oregon 

South  Carolina 
South  Dakota. . 

Texas 

Utah 

Washington . . . 
Others 

Total 

Canada , 


1890. 


Silver. 


1, 

1, 

24, 

4, 

20, 
5, 
1, 


10, 


§9,697 

292,939 

163,636 

307,070 

517 

783,838 

71,111 

363,636 

753,535 

680,808 

7,757 

96,969 

517 

129,292 

387,878 

343,434 

90,505 

2,585 


70,485,714 
518,000 


Gold. 


$762,500 

1,000,000 

12,500,000 

4,150,000 

100,000 

1,850,000 

90,000 

3,300,000 

2,800,000 

850,000 

118,500 
1,100,000 

100,000 
3,200,000 

6*80, 000 

204,000 

40,000 


32,845,000 
1,149,776 


1898. 


Silver. 


$147,500 

1,622,500 

442,500 

13,866,535 

3, '707, 999 

8,'743!6ii 
826,000 
383,500 

"'*75",7i2 

354,666 

354,000 

3,876,451 

206,500 

64,037 


34,670,245 
2,616,110 


Gold. 


$2,820,000 

2.800,000 

14,900,000 

23,534,531 

2,050,666 

5,247,913 

3,000,000 

480,000 

1,216,669 

5,'720',666 

'2,372,442 
600,000 
340,875 


65,082,430 
13,790.000 


The  above  figures  for  1890  are  from  the  Report  of  the  Director 
of  the  Mint  for  that  year.  The  figures  for  1 898  are  from  the 
Mineral  Industry,  VII.,  1899.  The  totals  illustrate  the  great 
falling  off  in  the  value  of  silver,  although  the  number  of  ounces 
was  actually  greater  in  1898  than  in  1890.  The  immense  in- 
crease in  the  output  of  gold  is  also  brought  out. 


CHAPTER  XIV. 

THE  LESSER  METALS:     ALUMINUM,     ANTIMONY,    ARSENIC, 
HROMIUM,    3 

ALUMINUM. 

2.14.01.  The  importance  of  aluminum  grows  with  improved 
and  cheaper  methods  of  production.  Its  sources  are,  or  have 
been,  alums,  either  natural  or  artificial,  corundum,  cryolite, 
kaolin  and  bauxite.  The  first  of  these  is  formed  in  nature  by 
the  decay  of  pyrite  in  shales  and  slates,  and  is  little  if  at  all 
used  as  an  ore  at  present.  The  second  is  more  valuable  as  an 
abrasive,  and  with  the  fall  in  the  price  of  the  metal  has  given 
way  to  other  and  cheaper  ores.  Still  corundum  (AI2O3)  with 
53.. 3  Al,  is  the  richest  natural  mineral.  Cryolite  and  bauxite 
are  now  the  staple  ores,  but  in  the  Grabau  process  kaolin  is 
employed,  although  not  as  yet  in  any  such  amount  as  these 
other  two.  The  fused  cryolite  plays  the  role  of  a  bath  in  which 
the  alumina  is  dissolved  and  reduced  bj^  electrolysis,  so  that 
really  bauxite  has  come  to  be  the  principal  source.  Cryolite 
occurs  as  an  immense  bedded  deposit  in  gneiss  at  Evigtok,  on 
the  Arksut  Fjord,  Greenland.  It  is  mined  as  an  open  cut,  and 
being  near  the  water's  edge,  on  a  steep  cliff,  after  hand-pick- 
ing, it  is  loaded  directly  upon  vessels,  which  moor  to  the  cliff. 
The  cryolite  is  associated  with  various  related  minerals,  all 
rare  and  mostly  limited  to  this  locality,  with  sulphides  of  iron, 
copper  and  lead,  and  with  siderite.  The  Pennsylvania  Salt 
Co.  of  Natrona,  Pa.,  receives  by  contract  two-thirds  of  the 
output,  the  remaining  third  going  to  Denmark.  The  other 
localties  of  this  mineral,  at  Miask,  in  the  Urals,  and  near  Pike's 
Peak,  Colo.,  are  small  and  commercially  unimportant  pockets. 


404  KEMP'S  ORE  DEPOSITS. 

Cryolite  when  pure  contains  13.02  Al,  and  of  itself  is  thus  a 
very  low  grade  ore/ 

2.14.02.  Bauxite  (AI2O3,  3H2O)  is  now  the  main  source  of 
the  metal.  In  the  pure  condition  and  of  the  composition  given 
above  it  contains  AI2O3,  65.55,  or  Al,  34.94,  but  various  im- 
purities are  always  with  it,  of  which  the  commonest  are  silica, 
oxide  of  iron,  oxide  of  manganese,  carbonates  of  lime  and 
magnesia,  phosphoric  acid,  and,  in  the  Southern  States,  sriiall 
but  constant  amounts  of  titanic  acid.  The  merchantable  ore 
ranges  from  about  40  to  over  60%,  or  even  over  70% 
AI2O3,  but  any  analysis  over  65.55%  AI2O3  indicates 
a  mineral  of  different  composition  from  AI2O3,  3H2O. 
There  is  no  doubt  that  such  exist,  and  in  an  interesting 
paper  entitled  **The  Bauxites :  A  Study  of  a  New  Mineralogical 
Family,''  M.  Francis  Laur^has  advocated  that  there  is  a  whole 
series  of  hydrated  compounds  of  alumina  which  are  as 
complex,  perhaps,  as  the  anhydrous  compounds  of  this  metal. 
Bauxite  is  now  known  to  occur  in  economic  quantities  in 
Georgia  and  Alabama,  and  in  Arkansas.  It  has  been  men- 
tioned, however,  from  numerous  other  points  in  States  immedi- 
ately north  of  the  two  former.  The  deposits  in  Georgia  and 
Alabama^  occur  along  a  narrow  belt  in  the  Coosa  Valley,  ex- 
tending some  sixty   miles  from   Adairsville,    Ga.,    to    Jack- 

*  On  the  geology  of  Greenland  Cryolite  see  G.  Hagermann,  ' '  On  some 
Minerals  associated  with  the  Cryolite  in  Greenland,"  Amer.  Jour.  Sci.. 
ii.,  XLII.,  93.  C.  Hart,  "On  the  Cryolite  Deposit,"  Jour,  of  Analyt.  and 
Applied  Chem.,  October,  1893.  G.  Lunge,  in  the  treatise  entitled,  "The 
Manufacture  of  Sulphuric  Acid  and  Alkali."  J.  W.  Taylor,  "Cryolite  of 
Evigtok,"  Quar.  Jour.  Geol.  Soc,  XII.,  140.  See  also  The  Mineral  Indus 
try,  Vols.  I.  and  II. ,  and  a  pamphlet  published  by  the  Pennsylvania  Salt 
Manufacturing  Co. 

2  Trans.  Amer.  Inst.  Min.  Eng.,  XXIV.,  234,  1894. 

^  C.  W.  Hayes,  "Geological  Relations  of  the  Southern  Appalachian 
Bauxite  Deposits,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXIV.,  243;  also  855, 
861,  1894.  Rec.  XVI  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey,  1894,  III.,  547. 
Rec.     H.  McCalley,  "Alabama  Bauxite,"  Proc.  Ala.  Indust.  and  Sci.  Soc, 

1893.  Reprinted  in  Science,  November  25, 1892,  p.  303 ;  a  later  paper  in  the 
issue  January  19,  1894,  p.  29.     "  Bauxite,"  in  The  Mineral  Industry,  II.,  57, 

1894.  Idem,  V.,  51.  Rec.  "Coosa  Valley  Region,"  Ala.  Geol.  Survey, 
1897.  Many  details  as  per  index.  E.  Nichols.  "An  Aluminum  Ore: 
Bauxite,"  Trans.  Amer.  Inst.  ^Min.  Eng.,  XVI.,  905.  R.  L.  Packard, 
"Aluminum,"  Mineral  Resources,  1891,  147.  J.  W.  Spencer,  "Geology 
and  Resources  of  Ten  Counties  in  northwestern  ^Georgia, "  p.  210, 1893.    Rec. 


THE  LESSER  METALS. 


405 


sonville,  Ala.  The  mineral  itself  is  pisolitic  or  oolitic 
in  structure,  as  a  general  thing,  and  the  individual 
masses  are  often  in  concentric  layers,  and  are  held  together 
either  by  non-oolitic  bauxite  or  by  silica.  Less  often  the  ore  is 
more  massive,  and  may  be  in  fairly  hard  lumps  or  soft  and 
earthy.  The  surface  ore  is  often  pitted  and  cellular.  The 
general  geological  relations  will  be  best  understood  by  referring 
to  Fig.  4,  p.  22.  The  region  is  largely  formed  by  Cambrian 
strata,  of  which  the  Connasauga  shales  are  the  upper  member, 
and  the  Rome  sandstone,  or  Weissner  quartzite,  is  the  lower. 
Above  the  Cambrian  is  found  the  Lower  Silurian,  Knox  dolo- 
mite, rich  in  chert.  These  strata  are  broken  by  folds  and  faults 
of  several  series  and  formed  at  different  periods.  The  great 
overthrust  shown  in  Fig.  4  is  of  post- Carboniferous  time,  long 


Fig.  3 


'mui 


r?.?-:- 


v.  ',2  ,  BAUXITE-  ."^  ..,  ; .  ->^?>Beoo5»  4^  ^^^^°25Btrk^=£^ 

•         '•     .  — <        .•'.   •     .*  .         ^.  '^^  x:-vvX>^;     •  TALUS   -N\\\ 


DEPTH  N0T1 
KNOWN " 


•      •      _ 

BOTTOM  or  PIT 


_' DRAINABE  niTCH ^.    -^ 

Bradley  i  Pbatet,  Ennr'a,  X  T. 


Fig.  154. — Crosa-section  of  a  Bauxite  deposit  in  Georgia.     After  (J.  Willard 
Hayes,  Trans.  Amer.  List:  Min.  Eng.,  February,  1894. 


after  the  principal  Appalachian  upheaval.  C.  W.  Hayes  has 
shown  that  the  ore  bodies  lie  along  certain  of  these  fault  lines, 
and  the  association  gives  us  a  possible  clue  to  their  method  of 
deposition.  They  are  very  sharply  limited  to  points  lying  be- 
tween the  900  and  950  feet  contours,  and  seem  to  have  been 
occasioned  by  the  attitude  of  the  land  toward  the  sea  during 
the  formation  of  the  Tertiary  peneplain  in  the  region. 

The  ores  are  always  found  in  the  residual  alteration  products 
of  the  Knox  dolomite,  from  which,  however,  they  are  quite 
sharply  separable.  The  accompanying  cross-section  shpws  the 
relations.  While  more  or  less  irregular  in  shape  they  have 
proved  quite  persistent,  and  many  3^ears'  supply  is  now  in 
sight.  Mr.  Hayes  suggests  that  the  crushing  attendant  on  the 
faulting,  developed  great  heat,  and   that   atmospheric   waters 


406  KEMP'S  QBE  DEPOSITS. 

penetrating  along  these  zones  became  charged  with  sulphuric 
acid,  derived  from  decomposing  pyrite.  The  acid  would  dis- 
solve alumina  from  the  Connasauga  shales,  possibly  forming 
alums,  with  some  alkali.  Calcium  carbonate  would  react  on 
such  solutions  so  as  to  precipitate  hydrate  of  alumina,  and  this, 
rising  as  a  flocculent  precipitate  in  springs,  gave  rise  to  the  ooli- 
tic and  pisolitic  deposits,  which  were  afterward,  in  the  decay 
of  the  Knox  dolomite,  involved  in  its  residual  products.  The 
explanation  is  reasonable  and  has  great  claims  to  confidence. 
The  same  general  hypothesis  may  be  applied  to  the  neighboring 
limonites.  H.  McCalley  gives  in  Science^  January  29, 1894,  p. 
30,  the  following  working  analyses  from  the  War- whoop  Bank. 
The  analyses  are  based  on  samples  from  car-load  lots,  and  repre- 
sent 500  to  1,000  tons.  The  first  column  is  the  variety  called 
**Hard  White  Ore";  the  second,  known  as  "War-whoop  Ore," 
is  the  average  of  consumer's  analyses. 

First.  •  Second. 

Alumina.. 57.-63.  56.-62. 

Ferric  oxide under  1.  3.5-3.0 

Silica,  about 3.50  5.00 

Titanic  acid 3.0-4.0  3.0-4.0 

Water,  combined 39.0-30.0  about  30.0 

Moisture,  hygroscopic 3.0-4.0  3.0-4.0 

A  little  over  half  (53.3%)  of  the  alumina  is  the  metal  itself. 

2.14.03.  The  bauxite  deposits  of  Arkansas  are  found  within 
a  few  miles  of  Little  Rock,  and  further  west  in  Saline  County, 
near  the  town  of  Bryant.  They  favor  the  contact  of  the  intruded 
syenites  (regarded  as  Cretaceous)  and  Paleozoic  sediments,  but 
they  are  themselves  involved  in  most  cases  in  Tertiary  sand- 
stones. The  association  with  syenite  is  quite  invariable.  The 
bauxite  is  pisolitic  and  concretionary.  The  range  in  composition 
is  considerable,  some  being  high  in  iron,  others  in  silica,  while 
others  are  fairly  pure.  The  variability  even  in  the  same  open- 
ing is  considerable,  as  indeed  is  always  the  case  with  deposits 
of  this  character.  The  deposits  are  individually  somewhat 
irregular  in  shape  and  extent,  but  the  quantity  is  large.  J.  C. 
Branner  regards  them  as  shore  deposits,  probably  formed  after 
the  manner  of  oolitic  concretions,  which  derived  their  hydrate 
of  alumina  from  the  syenite,  through  tho  medium  of  hot 
springs.     A  submergence  of  the  still  heated  syenite  beneath 


THE  LESSER  METALS.  A01 

«ea  water  is  suggested  as  a  possible  explanation  of  the  solution 
and  deposition.  Dr.  Branner  gives,  in  the  reference  from  the 
Journal  of  Geology,  cited  below,  a  complete  bibliography  and 
review  of  the  literature  on  bauxite  and  of  the  views  regarding 
its  origin.^ 

2. 14. 04.  W.  P.  Blake  has  descri bed  deposits  of  alunogen  and 
bauxite,  on  the  upper  Gila  Kiver,  about  40  miles  north  of  Sil- 
ver City,  New  Mexico.  The  bauxite  has  resulted  from  the 
action  of  sulphuric  acid,  produced  in  the  decay  of  pyrites,  upon 
basalts.  Alunogen  and  sulphate  of  iron  are  removed  while 
bauxite  remains  as  a  residual  deposit.  The  geological  relations, 
are  therefore  very  like  those  of  Glenariff,  County  Antrim, 
Ireland,  and  of  the  Vogelsberg,  Germany.^  The  Gila  River 
deposits  are  too  remote  for  utilization  under  present  conditions. 

Bauxite  is  employed  for  many  other  purposes  besides  fur- 
nishing an  ore  of  aluminum,  as  this  is  one  of  its  later  adapta- 
tions. Great  quantities  are  used  to  produce  alums,  and  as  a 
refractory  material  it  has  long  been  appreciated. 

2.14.05.  In  the  earlier  development  of  the  aluminum  indus- 
try corundum  was  somewhat  sought  as  an  ore.  The  varieties 
with  vitreous  luster  and  light  colors  are  called  sapphire,  the 
duller  and  more  smoky  ones,  corundum,  while  the  impure 
kinds,  which  are  mixed  more  or  less  with  magnetite,  hematite, 
spinel,  etc. ,  pass  under  the  name  of  emery.  The  last  named  is 
of  no  importance  in  this  connection.  Some  sapphire  and 
corundum  have  been  obtained  in  Chester  County,  Penn.,  but 
practically  the  only  source  of  any  moment  in  the  United  States 
is  in  a  belt  of  a  curious  rock  called  dunite,  which  consists  of 
grains  of  olivine,  and  which  traverses  western  North  Carolina 

*  J.  C.  Branner,  "Bauxite  in  Arkansas,"  Amer.  Geol,  VII.,  181,  1891. 
An  extended  report  was  announced  for  Vol.  I.,  1889,  of  Dr.  Branner's 
Annual  Reports  as  State  Geologist  of  Arkansas,  but  it  has  not  yet  (1899) 
been  issued.  Preliminary  reports  appear  in  the  Arkansas  Gazette  and 
Arkansas  Democrat,  Little  Rock,  January  8, 1891.  Third  Biennial  Report, 
Bureau  of  Mines,  Manufactures  and  Agriculture  of  the  State  of  Arkansas, 
for  1893  and  1894,  Little  Rock,  1894, 119-125.  Fourth  Biennial  Report,  Little 
Rock.  1896,  105-110.  "The  Bauxite  Deposits  of  Arkansas,"  Jour,  of  Geol, 
v.,  263, 1897.  J.  Francis  Williams,  Ann.  Rep.  Geol.  Survey  Ark.,  1880,  II., 
124. 

"  W.  P.  Blake,  "Alunogen  and  Bauxite  of  New  Mexico,"  Travis.  Amer. 
Inst  Mm.  Eng.,  XXIV.,  571. 


i08  KEMP'S  ORE  DEPOSITS. 

and  Georgia.  The  corundum  occurs  along  the  contacts  of  the 
dunite  and  a  hornblende  gneiss  with  which  it  is  associated. 
It  lies  in  scattered  lumps  distributed  through  decomposed 
micaceous  material,  which  is  at  times  so  soft  as  to  be  washed 
out  in  the  hydraulic  way.  In  some  instances  the  mineral  ap- 
pears to  have  resulted  from  some  reactionary  effects  of  the  two 
rocks,  or  of  solutions  emanating  from  them,  on  each  other. 
The  gneiss  is  aluminous,  the  dunite  magnesian.^  Again  it 
seems  to  have  crystallized  directly  from  fusion  and  to  have 
become  concentrated  near  the  walls,  either  from  the  operation 
of  Soret's  law,  or  from  convection  currents  as  described  under 
1.06.13.^  J.  H.  Pratt  has  even  been  able  to  apply  the  results 
experimentally  obtained  by  J.  Morozewicz  to  the  rocks  which 
yield  the  corundum,  and  has  made  the  following  summary  as 
the  result  of  his  observations  and  analyses,  dealing  in  all  cases 
with  peridotites. 

1.  When  the  magma  is  a  calcium -sodium-potassium  silicate, 
no  alumina  held  in  solution  will  separate  out  as  corundum,  ex- 
cept when  the  ratio  of  the  alumina  to  the  other  bases  is  more 
than  1 : 1,  and  the  ratio  of  the  silica  is  less  than  6.     (Molecular 

>  T.  M.  Chatard,  Mineral  Resources,  U.  S.  Qeol.  Survey,  1883-84,  714. 
Rec.  "The  Gneiss-Dunite  Contacts  of  Corundum  Hill,  N.  C,"  etc.,  Bull. 
U.  S.  Geol.  Survey,  XLII.,  45,  1881.  Rec.  Short  abstract  in  the  Eng.  and 
Min.  Jour.,  July  21,  1888,  p.  46.  J.  P.  Cooke,  Froe.  Amer.  Acad.,  IX.,  48, 
1874.  F.  A.  Genth,  "Corundum:  Its  Alterations  and  Associated  Min- 
erals," Amer.  Phil.  Soc,  September  19,  1873;  July  17,  1874;  Amer.  Jour. 
Sd.,  iii.,  VI.,  461,  1873.  T.  S.  Hunt,  Trans.  Roy.  Soc.  Can.,  II.,  1884.  C. 
W.  Jenks,  Quar.  Jour.  Geol.  Soc,  XXX.,  303,  1874.  A.  A.  Julien,  Proc. 
Post.  Soc.  Nat.  Hist,  XXII.,  131,  1893.  W.  C.  Kerr,  "Geology  of  North 
Carolina,  Supplement,"  64,  1875.  F.  P.  King,  "Preliminary  Report  on 
Corundum  Deposits  of  Georgia,"  Geol.  Survey  Georgia,  Bulletin  2,  1894. 
J.  V.  Lewis,  "Corundum  in  the  Appalachian  Crystalline  Belt,"  Trans. 
Am^r.  Inst.  Min.  Eng.,  XXV.,  832,  1895.  Rec.  R.  W.  Raymond.  "Jenks' 
Corundum  Mine,  N.  C,"  Trans.  Amer.  Inst.  Min.  Eng.,  VII.,  83,  1878. 
C.  U.  Shepard,  "On  the  Corundum  Region  of  North  Carolina  and  Geor- 
gia," Amer.  Jour.  Sci.,  iii.,  IV.,  109,  175, 1872.  Rec.  C.  D.  Smith,  "Geol 
ogy  Noi-th  Carolina,  I.,  Appendix  D.,"  91,  1875;  II.,  43,  1881.  J.  L.  Smith 
" Notes  on  the  Corundum  of  North  Carolina,  Georgia,"  etc.,  Amer.  Jour. 
Sci.,  iii.,  VI.,  180,  1873.  Rec.  M.  E.  Wadsworth,  Mem.  Mus.  Comp.  Zool, 
XL,  Part  I.,  p.  118,  1884. 

'J.  H.  Pratt,  "On  the   Origin  of  the  Corundum  Associated   with  the 
Peridolites  in  North  Carolina,"  Amer.  Jour.  Sci.,  July,  1898,  p.  49. 


THE  LE88ER  METALS.  409 

ratios  are  meaot,  i.e.,  the  quotients  obtained  by  dividing  the 
percentage  by  the  molecular  weight  in  each  case.) 

2.  If  magnesia  and  iron  are  present  in  the  above  magma, 
corundum  will  not  form  unless  there  is  more  than  enough 
alumina  to  unite  with  the  magnesia  and  iron  (that  is,  spinels 
will  form  in  preference  to  corundum  where  possible). 

3.  When  the  magma  is  composed  of  a  magnesium  silicate 
without  excess  of  magnesia,  all  the  alumina  held  by  such  a 
magma  will  separate  out  as  corundum. 

4.  Where  thare  is  an  excess  of  magnesia  in  the  magma  just 
described,  this  will  unite  with  a  portion  of  the  alumina  to  form 
spinel,  and  the  rest  of  the  alumina  will  separate  out  as  corun- 
dum. 

5.  Where  there  is  chromic  oxide  in  a  magma  composed  es- 
sentially of  a  magnesium  silicate  (as  the  peridotite  rocks),  and 
only  a  very  little  alumina  and  magnesia  are  present,  these, 
uniting,  separate  out  with  chromic  oxide  to  form  the  mineral 
chromite,  and  no  corundum  or  spinel  is  formed. 

6.  When  peridotite  magmas  contain,  besides  the  alumina, 
oxides  of  the  alkalies  and  alkali-earths,  as  soda,  potash  and 
lime,  a  portion  of  the  alumma  is  used  in  uniting  with  these 
oxides  and  silica  to  form  feldspar. 

7.  There  is  a  strong  tendency  for  the  alumina  to  unite  with  the 
alkali  and  alkali-earth  oxides,  to  produce  double  silicates  like 
feldspars,  whether  such  silicates  form  the  chief  minerals  of  the 
resulting  rock,  or  are  present  only  in  relatively  small  amount. 
There  is,  however,  but  little  tendency  for  the  alumina  to  unite 
with  magnesia,  to  form  double  silicates,  when  the  magma  is  a 
magnesium  silicate.^ 

2.14.06.  The  most  important  recent  discovery  of  corundum 
in  commercial  quantities  is  that  of  the  deposits  associated  with 
the  belt  of  nepheline  syenite  that  covers  a  large  area  in  eastern 
Ontario,  north  of  Kingston.  The  syenite,  which  is  at  times 
very  coarsely  crystalline  and  pegmatitic,  contains  crystals  of 
corundum,  often  of  large  size  and  of  considerable  regularity  of 
form.  Blue  sodalite  also  occurs  in  the  rock  in  large  masses. 
Experiments  in  concentration  have  been  carried  on  at  the 
School  of  Mines  in  Kingston  under  Professor  Miller,  and  actual 

^  J.  H.  Pratt,  "On  the  Separation  of  Alumina  from  Molten  Magmas, 
and  the  Formation  of  Corundum,"  Amer.  Jour.  Set,  September,  1892,  227. 


4:10  KEMP'S  ORE  DEPOSITS. 

development  is  probable  at  an  early  date.^  Corundum  of  gem 
grade  has  been  mined  at  Yogo  Gulch,  Mont.,  and  beautiful 
sapphires  are  obtained.^  The  commercial  emery  employed  in 
America  is  largely  imported  from  Smyrna,  but  it  has  no  bear- 
ing on  the  production  of  aluminum.  It  is  also  mined  at  Ches- 
ter, Mass.,  and  near  Peekskill,  N.  Y.^  Corundum  is  reported 
in  vast  amount  in  India.* 

ANTIMONY. 

Senarmontite,  SbgOs;  Sb.  83.56;  O.   16.44, 
Stibnite  (Antimonite,  Antimony  Glance),  Sb2S3;    Sb.  71.8; 
S.  28.2. 

2.14.07.  Antimony  occurs  in  composition  with  several  silver 
ojes,  but  almost  its  sole  commercial  source  is  stibnite.  The 
oxide,  senarmontite,  is  rarely  abundant  enough  to  be  an  ore. 
Stibnite  was  one  of  the  minerals  formerly  cited  as  having 
originated  in  veins  bj'  volatilization  from  lower  sources.  But 
it  has  probably,  in  all  cases,  been  derived  from  solutions  of 
alkaline  sulphides. 

2.14.08.  Example  47.  Veins  containing  stibnite,  usually  in 
quartz  gangue.  California,  Kern  County.  At  San  Emigdio 
a  vein  of  workable  size  has  been  found.  It  has  a  quartz  gangue 
and  is  in  granite.  The  vein  varies  from  a  few  inches  to  several 
feet  across,  and  has  afforded  some  metal.  Several  others  are'*^^^^"^ 
known  in  San  Benito  and  Inyo  counties. 

*  F.  D.  Adams,  **  Report  on  the  Geology  of  a  Portion  of  Central  Ontario," 
Geol.  Survey  Can.,  1892-3,  Report  J,  5.  •'  Occurrence  of  a  Large  Area  of 
Nepheline  Syenite  in  the  Township  of  Dungannon,  Ontario,"  Amer.  Jour. 
Sci. ,  July,  1894,  10.  (The  corundum  had  not  been  discovered  when  these 
two  papers  were  issued.)  Archibald  Blue,  "Corundum  in  Ontario," 
Amer.  Inst.  Min.  Eng.,  Buffalo  meeting,  1898.  A.  P.  Coleman,  "Corun- 
diferous  Nephehne-Syenite  from  Eastern  Ontario,"  Jour.  Geol,  VII., 
July- August,  1899,  437.  B.  J.  Harrington,  "Nepheline,  Sodalite  and 
Orthoclase  from  the  Nepheline  Syenite  of  Dungannon,  Ont.,"  Amer.  Jour. 
Sci.,  July,  1894.  16.  W.  G.  Miller,  "  Report  of  Ontario  Bureau  of  Mines," 
VII.,  207,  1898. 

*  L.  V.  Pirsson,  "Corundum-bearing  Rock  from  Yogo  Gulch,  Mont.," 
Amer.  Jour.  Sd.,  December,  1897,  421. 

3  J.  D.  Dana,  Amer.  Jour.  Sci.,  September,  1880,  199.  J.  P.  Kimball, 
Amer.  Chemist,  IV.,  1874,  321.  Trans.  Amer.  Inst.  Min.  Eng.,  IX.,  19, 
1881.     G.  H.  Williams,  Amer.  Jour.  Sci,  March,  1887,  197.     Rec. 

*  T.  H.  Holland,  "Corundum":  in  "A  Manual  of  the  Geology  of  India," 
Economic  Geol,  Part  I.,  1898,  1-69. 


THE  LESSER  METALS.  411 

2.14.09.  Nevada,  Humboldt  County,  Stibnite  has  been 
known  for  some  years  in  veins  with  quartz  gangue.  The 
Thies-Hutchens  mines,  about  15  miles  from  Lovelock  station, 
were  productive  in  1891.  Lander  County.  The  most  impor- 
tant of  the  American  mines  are  the  Beulah  and  Genesee,  at  Big 
Creek,  near  Austin.  The  vein  is  reported  as  showing  three 
feet  of  nearly  pure  stibnite.  It  produced  700  tons  of  sulphide  in 
1891,  and  was  operated  in  1892. 

2.14.10.  Arkansas,  Sevier  County.  Stibnite  occurs  in  veins 
with  quartz  gangue  in  southwestern  Arkansas.  Some  attempts 
have  been  made  to  develop  them,  but  the  ore  is  reported  to  be 
too  remote  for  profitable  working.  The  veins  appear  to  be  gen- 
erally interbedded  in  Trenton  shales  and  to  lie  along  anticlinal 
axes,  which  trend  northeast.  They  are  all  controlled  by  the 
United  States  Antimony  Company,  of  Philadelphia. 

2.14.11.  New  Brunswick,  York  County.  Veins  of  quartz 
or  quartz  and  calcite,  carrying  stibnite,  occur  over  several 
square  miles.  The  wall  rocks  are  clay  slates  and  sandstones  of 
Cambro-Silurian  age.  The  mines  have  been  commercially  pro- 
ductive.    The  veins  vary  from  a  few  inches  to  six  feet. 

2.14.12.  Example  48.  Utah,  Iron  County.  Disseminations 
of  stibnite  in  sandstone  and  conglomerate,  following  the  strati- 
fication. In  Iron  County,  southwestern  Utah,  masses  of  radiat- 
ing needles  occur  in  sandstones  and  between  the  boulders  of  an 
associated  conglomerate.  Very  large  individual  pieces  have 
been  obtained,  but  not  enough  for  profitable  mining.  Blake 
thinks  that  the  ore  has  crystallized  from  descending  solutions. 
Eruptive  rocks  are  present  above  the  sandstones. 

2.14.13.  An  interesting  deposit  of  senarmontite  was  worked 
for  a  time  in  Sonora,  just  south  of  the  Arizona  line,  but  it  was 
soon  exhausted.^ 

^  General  References:  W.  P.  Blake.  "General  Distribuoion  of  Ores  of 
Antimony,"  Min.  Resources  of  the  U.  S.,  1883-84,  p.  641.  Arkansas:  T,  B. 
Comstock,  Oeol.  Survey  of  Kan.,  1888,  I.,  p.  136.  F.  P.  Dunnington, 
"Minerals  of  a  Deposit  of  Antimony  Ores  in  Sevier  County,  Ark.,"  Amer. 
Assoc.  Arts  and  Sci.,  1877.  Rec.  J.  W.  Mallet,  Chem.  News,  No.  533.  C. 
E.  Waite,  "Antimony  Deposits  of  Arkansas,"  Trans.  Amer.  Inst.  Min. 
Eng.,  VII.,  43.  C.  P.  Williams,  "  Notes  on  the  Occurrence  of  Antimony 
in  Arkansas,"  Idem,  III..  150.  California:  W.  P.  Blake,  "Kern  County," 
U.  S.  Pac.  R.  R.  Explor.  and  Survey,  Vol  V.,  p.  291.  H.  G.  Hanks, -Rep. 
Cal.  State  Mineralogist,  1884.      See  also  subsequent  reports  by  William 


412  KEMP'S  ORE  DEPOSITS. 

ARSENIC. 

2.14.14.  This  metal  occurs  with  many  silver  ores  in  the 
West  and  in  arsenopyrite,  or  mispickel,  a  not  uncommon  arseno- 
sulphide  in  the  gold  quartz  veins,  east  and  west.  At  the  Gat- 
ling  mines,  in  the  town  of  Marmora  (more  lately  called  Deloro), 
in  Hastings  County,  Ontario,  auriferous  mispickel  occurs  in 
great  quantity  in  granite,  in  veins  with  quartz  gangue.  Con- 
siderable oxide  of  arsenic  has  been  obtained  in  the  past  from 
the  roasters,  but  in  recent  years  the  cyanide  process  has  been 
employed.  For  reference  to  the  printed  descriptions  see  under 
"Gold  in  Canada"  (2.13.07).  Considerable  arsenic  is  also  pro- 
duced as  a  by-product  in  treating  the  ores  of  the  Monte  Cristo 
mines  of  Washington  State. 

BISMUTH. 

2.14.15.  Bismuth  occurs  with  certain  silver  ores  in  the  San 
Juan  district,  Colorado,  and  is  referred  to  in  the  description  of 
the  country  under  ** Silver  and  Gold"  (2.09.10).  Lane's  mine, 
at  Monroe,  Conn.,  has  furnished  museum  specimens  of  native 
bismuth  in  quartz.  Some  neighboring  parts  of  Connecticut 
have  afforded  bismuth  minerals,  and  not  a  few  other  places  in 
the  country  contain  traces,  but  the  San  Juan  is  the  only  serious 
one  as  yet/ 

CHROMIUM. 

2.14.16.  Chromite,  whose  theoretical  composition  is 
FeO.CrgOs,  with  CrgOs  68%,  often  has  MgO  and  FegOs  re- 
placing its  normal  oxides.  The  percentage  of  CraOs  is  thus 
reduced.  It  is  always  found  in  association  with  serpentine, 
which  has  resulted  from  the  alteration  of  basic  rocks  consisting 
of  olivine,  hornblende,   and  pyroxene.     These  minerals,  or  at 

Irelan,  Jr.  Mexico:  E.  T.  Cox,  "Discovery  of  Oxide  of  Antimony  in  So- 
nora,"  Amer.  Jour.  Set.,  XX.,  431.  J.  Douglass,  "The  Antimony  Deposit 
of  Sonora,"  Eng.  and  Min.  Jour.,  May  21,  1881,  p.  350.  Nevada:  Idem, 
1892,  p.  6.  New  Brunswick:  L.  W.  Bailey,  "Discovery  of  Stibnite  in 
New  Brunswick,"  Amer.  Jour.  Sci.,  ii.,  XXXV.,  150,  and  in  Rep.  on  the 
Geol.  of  New  Brunswick,  1865 ;  also  H.  Y,  Hind,  in  the  same.  Utah :  D. 
B.  Huntley,  Tenth  Census-,  Vol.  XIII.,  p.  463. 

*  Min.  Resources  of  the  U.  S.,  1885,  p.  399.     B.  Silliman,  "  Bismuthinite 
from  the  Granite  District,  Utah,"  Amer.  Jour.  Sci.,  iii.,  VI.,  123.     H.  L. 
Wells,  " Bismuthosphaerite  from  Williraantic  and  Portland,  Conn.,"  Amer 
Jour.  Sci.,  iii.,  XXXIV.,  271 


THE  LESSER  METALS.  413 

least  the  pyroxenes,  contain  chromium  as  a  hase,  but  in  the 
unaltered  rock  there  is  no  question  that  chromite  itself  has 
formed  one  of  the  component  minerals,  just  as  magnetite  so 
commonly  occurs  in  this  relation.  A  chrome  spinel,  picotite  is 
also  not  unusual.  The  basic  rocks,  peridotites  and  pyroxenites, 
almost  alwaj^s  yield  on  analysis  some  chromic  oxide,  and  may 
in  extreme  cases  afford  several  per  cent.  Vogt  gives  in  the 
paper" cited  below  a  series  of  percentages  from  0.25  to  3.55  in 
twelve  peridotites,  from  various  localities.  The  invariable 
association  of  the  metal  with  rocks  rich  in  magnesium  is  strik- 
ing. Inasmuch  as  the  chromite  occurs,  when  mined,  in  ser- 
pentine, a  secondary  rock,  it  has  usually  been  believed  that  it 
was  a  product  set  free  in  the  change  from  the  anhydrous 
original  to  the  hydrated  derivative.^  Meunier  has  referred  it 
to  the  action  of  vapors  or  to  a  pneumatolj'tic  process  in  the 
still  molten  peridotite  magma.  Vogt,  however,  includes  the 
chromium  ore  bodies  in  the  category  of  those  formed  by  direct 
crystallization  from  a  molten  magma,  and  regards  the  chromite 
of  the  serpentines  simply  as  the  original  crystallizations  which 
have  resisted  alteration,  while  their  associated  minerals  have 
undergone  hydration  and  change.  As  chromite  is  a  mineral 
that  is  extremely  resistant  to  the  action  of  the  natural  solvents 
and  reagents,  this  view  has  much  to  commend  it.  Dynamic 
raetamorphism  might  afterward  drag  out  the  masses  of  chro- 
mite into  a  lineal  alignment.  Vogt  also  describes  a  fresh  perid- 
otite from  Hestmando  under  the  polar  circle  in  the  extreme 
north  of  Norway,^  that  is  almost  or  quite  rich  enough  in 
chromite  to  be  worthj^  of  exploitation.  Hydrated  nickel  com- 
pounds are  often  associated  with  chromite. 

In  recent  investigations  of  the  chromite  deposits  of  North 
Carolina,  J.  H.   Pratt  ^  has   reached   the  conclusion   that  the 

*  See  in  this  connection  the  following,  which  are  cited  by  Vogt,  Cossa 
and  Arzruni,  Zeitschr  f.  Krystal,  VII.,  p.  1,  1883.  A.  v.  Groddeck, 
Lehre  von  den  Lagerstdtten  der  Erze,  146,  1879.  A.  Helland,  Gesellsch. 
der  Wissenschaften-Kristiania,  1873.  L.  de  Launay,  Formation  Oites 
Metalliferes,  1893. 

^  J.  H.  L.  Vogt,  Zeits.  fur  prakt.  Oeol. ,  1894,  385.  L.  de  Launay  sup- 
ports the  same  view,  Annales  des  Mines,  XII.,  1897,  175. 

^  J.  H.  Pratt,  "  On  the  Occurrence,  Origin  and  Chemical  Composition 
of  Chromite,"  Trans.  Amer.  Inst.  Min.  Eng.,  New  York  meeting,  Feb- 
ruary, 1899.  Abstract  in  Eng.  and  Min.  Jour.,  December  10,  1898.  Re- 
fers especially  to  North  Carolina. 


414  KEMP'S  ORE  DEPOSITS. 

mineral  has  crystallized  from  fusion,  and  has  become  concen- 
trated near  the  walls  by  convection  currents,  as  described  un- 
der 1.06.13. 

2.14.17.  The  chromite  of  commerce  should  contain  at  least 
50%  CrgOs.  Values  over  this  command  a  premium,  while 
those  below  50  suffer  severe  rebates.  The  less  silica,  the 
better.  Wm.  Glenn  cites  the  following  three  analyses  as 
typical  of  the  run  of  the  commercial  product,  the  sources  of  the 
ore  not  being  given.  (XVll,  Annual  Report  Director  U.  S. 
Geol  Soc,  Part  III,  263.) 

SiOg 7.00  5.22  6.44 

Cr^Og 39.15  51.03  53.07 

FeO 27.12  13.06  15.27 

MgO 16.11  16.32  16.08 

CaO 3.41  2.61  1.20 

AlgOg 7.00  12.16  8.01 

99.79  100.40  100.07 

Chromite  in  the  arts  is  chiefly  employed  in  the  manufacture 
of  potassium  or  sodium  bichromate,  so  essential  to  dyeing,  but 
of  late  years  it  is  also  proving  of  great  value  as  an  ingredient 
of  refractory  bricks,  and  as  a  lining  for  furnaces. 

2.14.18.  Example  49.  Disseminations  of  chromite  in  ser- 
pentine. Pennsylvania  and  Maryland.  Great  areas  of  serpen- 
tine are  found  in  southeastern  Pennsylvania  and  in  the  adja- 
cent parts  of  Delaware  and  Maryland.  Considerable  mining 
has  been  done  in  the  past.  Where  first  obtained  the  chromite 
occurred  in  loose  masses  in  the  residual  soil  on  the  surface.  It 
was  identified  and  gathered  in  Harford  County,  Maryland,  as 
early  as  1827  by  Isaac  Tyson,  Jr.,  and  found  a  ready  market 
abroad,  to  such  an  extent  that  from  1827  to  1860  the  Baltimore  re- 
gion was  the  chief  source  of  the  mineral  for  the  world.  In  the  ser- 
pentines of  neighboring  parts  of  Maryland  and  in  southeastern 
Pennsylvania  other  deposits  were  found  in  the  years  following 
1827,  and  a  very  important  industry  sprang  up.  The  largest 
proved  to  be  the  Wood  Pit  or  Mine  in  Lancaster  County,  Penn- 
sylvania, and  it  developed  the  most  productive  single  deposit 
yet  known.  It  has  been  worked  to  a  depth  of  700  feet  or  more 
— a  striking  thing  for  chromite,  whose  deposits,  as  a  rule,  are 
very  limited  in  depth  and  extent,  and   very  pockety.     The  so- 


THE  LESSER  METALS.  415 

called  Texas  mine  near  or  on  the  Maryland-Pennsylvania  line 
also  became  well  known.  In  addition  to  the  surface  boulders 
and  included  masses,  chromite  sand  of  commercial  grade  has 
been  obtained  from  the  beds  of  streams  in  this  belt,  and,  as 
stated  by  Wm.  Glenn,  the  supply  is  renewed  after  an  interval 
of  about  fifteen  years.  The  work  of  G.  H.  Williams  and  F.  D, 
Chester  has  shown  the  great  abundance  of  basic,  plu tonic  rocks, 
gabbros,  pyroxenites,  peridotites  and  the  like  in  this  region, 
and  there  is  every  reason  to  regard  the  serpentines  as  derivatives 
from  such  originals.  During  the  process  of  alteration  what- 
ever chromite  there  was  present  in  the  fresh  igneous  rock, 
was  reinforced  by  the  formation  of  secondary  chromite  from  the 
alteration  of  chromiferous  pyroxene,  and  other  minerals,  but 
only  rarely  were  sufficient  amounts  produced  to  warrant  min- 
ing. Dynamic  metamorphism  may  have  strung  them  out  in 
linear  alignment. 

2.14.19.  Chromite  has  also  been  met  in  several  places  in  the 
south,  but  never,  as  yet,  in  minable  amounts.  The  Baltimore 
region  itself  has  not  been  active  for  some  years. ^ 

2.14.20.  California.  As  already  mentioned  under  the  pre- 
cious metals,  great  areas  of  serpentine  occur  on  the  western 
flanks  of  the  Sierras  and  in  the  Coast  range.  In  Del  Norte, 
San  Luis  Obispo,  Placer,  and  Shasta  counties,  California,  they 
furnish  commercial  amounts  of  chromite.  In  some  places  the 
ore  is  followed  by  underground  mining,  and  in  others  it  is 

'  F.  D.  Chester,  in  the  Ann.  Rep.  Penn.  Geol.  Survey,  1887,  describes 
the  Serpentine  along  the  State  line  with  Delaware.  D.  T.  Day,  Mineral 
Resources,  and  since  1894,  Ann.  Reps.  oftheDir.  of  U.  S.  Geol.  Survey,  1882, 
p.  428;  especially  1883-84,  p.  567.  J.  Eyerman,  "On  Woods  Mine,  Pa.,"  Min- 
eralogy of  Penn. ,  Easton,  1889.  P.  Eraser,  ' '  The  Northern  Serpentine  Belt 
in  Chester  County,  Pa.,"  Trans.  Amer.  Inst.  Min.  Eng.,  XII.,  349.  Report 
C3,  Lancaster  Co.,  Penn.,  Geol.  Survey.  Rec.  T.  H.  Garrett,  "Chemical 
Examination  of  Minerals  Associated  with  Serpentine,"  Amer.  Jour.  Sci., 
ii.,  XIII.,  45,  and  XV.,  332.  F.  A.  Genth,  Idem,  ii.,  XLL,  120.  Wm. 
Glenn,  "Chrome  in  the  Southern  Appalachian  Region,"  Trans.  Jlmer. 
Inst.  Min.  Eng.,  XXV.,  481.  Rec.  J.  H.  Pratt,  "The  Occurrence,  Origin 
and  Chemical  Composition  of  Chromite,"  Trans.  Amer.  Inst.  Min.  Eng., 
February,  1899,  New  York  meeting.  G.  H.  Williams,  "The  Gabbros  and 
Associated  Hornblende  Rocks  near  Baltimore,"  Bull.  23,  U.  S.  Geol. 
Survey.  "  The  Geology  of  the  Crystalline  Rocks  near  Baltimore,"  dis- 
tributed at  the  Baltimore  meeting  of  the  Amer.  Inst.  Min.  Eng. ,  Feb- 
ruary, 1892.     Rec. 


4]  6  KEMP'S  ORE  DEPOSITS. 

gathered  as  float  material.  The  irregular  distribution,  always 
characteristic  of  the  mineralj  renders  underground  work  uncer- 
tain. Good  ore  should  afford  50%  Cr203,  and  in  California  no 
ore  less  than  47%  is  accepted.  It  brings  in  the  East  $22  to 
$35  per  ton.^ 

2.14.21.  Quebec.  In  the  serpentine  belt  that  extends  from 
northern  Vermont  to  Gaspe,  and  which  contains  the  well 
known  asbestos  mines  near  Black  Lake,  chromite  has  been 
known  for  many  years.  In  1894  some  productive  pockets  were 
found  that  have  since  yielded  about  three  thousand  tons  of  high 
grade  ore.  The  mines  are  two  miles  from  Black  Lake  station, 
and  are  in  a  belt  of  serpentine  south  of  the  asbestos  belt.  In 
the  best  pocket  the  ore  occurred  next  a  dike  of  granulite,^  ac- 
cording to  Donald,  but  elsewhere  it  lacks  this  associate. 

2.14.22.  Newfoundland.  Chromite  has  verj'  recently  been 
discovered  and  developed  at  Port  au  Port  Bay,  on  the  west  coast 
of  Newfoundland.  G.  W.  Maynard  states  that  it  occurs  in 
bands  of  serpentine,  which  are  themselves  enclosed  in  diorite. 
The  geological  surroundings  are  thus  those  of  the  usual  ser- 
pentinous  and  basic  igneous  rocks.  The  quantity  exposed  war 
ranted  the  erection  of  a  concentrating  plant. ^ 

COBALT    (see   under  " NICKEL"). 
MANGANESE. 

2.14.23.  Ores:  Pyrolusite  MnOg,  Mn.  63.2,  braunite,  Mn2  03, 
Mn  69.62.  Some  SiOa,  which  may  be  chemically  com- 
bined, is  usually  present,  and  small  amounts  of  MgO,  CaO, 
etc.  Psilomelane  has  no  definite  composition,  but  usually  con- 
tains barium  or  other  impurities.  An  Arkansas  variety  has 
afforded  Brackett  MnO,  77.85. 

*  E.  Goldsmith,  "  Chromite  from  Monterey  County,  Cal.,"  Proc.  Phila. 
Acad.  Set,  1873,  365.  Wm.  Irelan,  Jr.,  Reports  of  Col.  State  Mineralo- 
gist, especially  1890,  pp.  167,  189,  313,  582,  583,  638.  J.  J.  Crawford  be- 
came State  Mineralogist  in  1893 ;  Chromite  receives  mention  also  in  his 
reports. 

"  J.  T.  Donald,  "Chromic  Iron  in  Quebec,"  Eng.  aud  Min.  Jour.,  Sep- 
tember 8,  1894,  224.  M.  Penhale,  Idem,  December  8,  1894,  532.  Wni. 
Glenn.  'Chromic  Iron,  with  Reference  to  its  Occurrence  in  Canada," 
XVII.  Ann.  Rep.  Dir.  U.  S.  Geol.  Survey,  Part  III.,  261.  Rec.  Contains 
a  good  bibliography.     J.  Obolski,  Can.  Min.  Review,  January,  1896. 

^  Geo.  W.  Maynard,  "The  Chromite  Deposits  on  Port  au  Port  Bay, 
Newfoundland,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXVII.  283,  1897. 


THE  LESSER  METALS.  417 

There  are  various  other  oxides  and  hydroxides,  which  are 
rarely  abundant  enough  to  be  ores.  The  carbonate,  rhodochro- 
site  and  the  silicate,  rhodonite,  are  rather  common  gangue 
minerals  with  ores  of  the  precious  metals.  Franklin ite  is  also 
an  important  source  (2.07.04).  Pyrolusite  and  psilomelane  are 
the  commonest  ores  the  country  over,  but  braunite  is  the  one  in 
the  Batesville  (Ark.)  region.  Manganese  is  widely  dis- 
tributed, and  yet  is  commercially  important  in  but  few  locali- 
ties. It  imitates  limonite  very  closely  in  its  occurrence,  and 
is  often  associated  with  this  ore  of  iron.  To  make  a  manganese 
ore  valuable,  at  least  40%  metallic  manganese  should  be  pres- 
ent, and  this  is  a  lower  limit  than  was  formerly  admissible 
when  the  ores  were  chiefly  used  in  chemical  manufactures. 
Under  present  conditions,  if  iron  is  present,  the  ore  may  be 
suited  to  Spiegel,  although  even  lower  in  manganese  than 
40%.  Further,  there  should  be  low  phosphorus;  Penrose  says 
not  over  0.2  to  0.25%  in  Arkansas,  and  not  over  12%  SiOg. 
High-grade  ores  run  50  to  60%  manganese. 

2.14.24.  The  original  home  of  manganese  is  in  the  ferro- 
magnesian  silicates  of  the  igneous  rocks.  In  all  of  them  it  is 
known  to  enter  as  a  minor  base,  acting  much  in  the  same  way 
as  iron.  On  being  released  from  the  ferro-magnesian  minerals, 
its  subsequent  geological  behavior  is  in  some  respects  much  like 
that  of  iron,  but  it  diff!er&  from  iron  in  that  its  sulphides,  though 
known,  are  very  rare  minerals.  Aqueous  circulations  leach  the 
manganese  from  the  igneous  rocks,  whether  deep-seated  or 
superficial,  and  sea- water  has  a  strong  dissolving  effect  upon 
fragmental,  volcanic  ejectments  that  are  thrown  into  the 
ocean.  In  the  latter  case  the  peroxide  of  manganese  finally 
forms  pellets  and  incrustations  on  the  sea -bottom,  especially  at 
great  depths;^  in  the  former  rhodonite  and  rhodochrosite  result 
as  the  familiar  gangue  minerals  of  many  veins,  and  manganese 
oxide  or  carbonate  enters  into  many  f ragmen ta J  sediments  and 
limestones.  Almost  all  the  deposits  of  commercial  importance 
have  been  produced   by  the  subaerial   alteration  of  these  last 

^  For  a  short  review  of  Manganese  in  Nature  see  L.  de  Launay,  Annales 
des  Mines,  XII.,  1897,  185-191.  The  subject  is  discussed  at  length  in  Pen- 
rose's Report  on  Manganese  for  the  Arkansas  Geol.  Survey.  Chapter  XXI. 

2  John  Murray,  Proc.  Boy.  Soc,  London,  XXIV.,  528.  Sir  C.  Wyville 
Thomson,  T7ie  Atlantic,  II.,  14,  1873. 


418 


KEMP'S  ORE  DEPOSITS. 


named,  so  that  nodules  of  manganese  oxides  remain  embedded 
in  residual  clays,  precisely  like  many  brown  hematite  deposits. 
2.14.25.  Example  50.  Manganese  ores,  chiefly  psilomelane 
and  pyrolusite,  often  in  concretionary  masses,  disseminated 
through  residual  clay,  which  with  the  ores  has  resulted  from  the 
alteration  of  limestones  and  shales.  The  deposits  are  entirely 
analogous  to  Examples  2  and  2a,  under  "Iron.''  Along  the 
Appalachians  the  favorite  horizon  is  just  over  the  Cambrian 
(Potsdam)  quartzite.  This  is  the  case  at  Brandon  and  South 
Wallingford,  Vt.,  where  the  ores  occur  in  a  great  bed  of  clay 
between  quartzite  and  limestone.  They  are  referred  to  under 
Example  2a,  where  mention  is  made  of  the  associated  limonites 


SECTION  NO.  2. 

SECTION  NO.  4. 

Fig.  155. — Sections  of  the  Crimora  manganese  mine,  Virginia.     T.Tie  trough  is 

formed  by  Potsdam  sandstone  a7id  is  filled  with  clay  carrying  nodules 

of  ore.     After  0.  E.  Hall,  Trans.  Amer.  Inst.  Min.  Eng., 

XX.,  48,  June,  1891. 

and  interesting  lignite.  They  have  never  been  important  pro- 
ducers of  manganese.  Crimora,  in  Augusta  County,  Va.,  was 
formerly  the  largest  mine  in  the  country'.  The  containing  cla}' 
bed  is  very  thick,  as  a  drill  hole,  276  feet  deep,  failed  to  strike 
rock.  The  ores  occur  in  pockets,  which  as  a  maximum  are  5  to  6 
feet  thick  and  20  to  30  feet  long,  and  of  lenticular  shape. 
Other  irregular  stringers  and  smaller  masses  run  through  the 
clay,  which  preserves  the  structure  of  the  original  rock.  Pots- 
dam quartzite  underlies  it.  Other  similar  bodies  occur  at  Lynd- 
hurst  and  elsewhere  in  the  Great  Valley  of  Virginia,  but 
Crimora  is  now  no  longer  a  source  of  ore.     Cartersville,  Ga., 


THE  LESSER  METALS. 


419 


IDEAL  Sections  showing  the/ormation  of  manganese-Bearing 

CLAY  FROM  THE  DECAY  OF  THE  ST. CLAIR  LIMESTONE. 
^m  n— I 

Boone  Chert  ^^  Manganesc-BEaRinQ  Clay  L_1JIzaR0  LimestonC 

SACCMAROfDAL  SANOSTONC 


St.Cuaib  limestone 


^--'=^-_ — ~  Z:^'      r  — --^'— _r-—         -r=—        ^IS"     ^ — -  _  -  _^- 

- — < 

zr2 

kr^F^S-^t^^^lSb^^-EbE^^^^&g 

H 

'    1    '    1     '    1        1        1        1        1        1        1         1        1         1        1 

j^ 

1       '        1      '        1'              1              1               II               II               1               III! 

•-r] 

— ' — T"      r               1        1        1         1         1        1         1         I         1        1 

T^ 

1    '    1    '     1    '    1    '    1    '    1    '     1    '     1        1         1    '■  1    '     1    '     1    '    1 

xrl 

'    1         1 1         1         1         1        1 

^Ufv 

II        1        1        1        1        1         II         1         1        1        II 

^ 

-.'■'■<■}  ■:y  :['■'■:■■/:  ■■\'':^//y:' :■'■'■■  :''-::'^^                                                                  ■■-. 

/ 

Fig.  1.— Original  Condition  oe  the  Rocks. 


Fig.  2.  —First  Stage,  of  Decomposition. 


Fig.  3.— Second  Stage  of  Deco:w position-. 


Fig.  4.— Third  Stage  of  Decomposition. 

Fig.  156. — Geological  sections  illustrating  the  formation  of  the  manganese  ores 

in  Arkansas.     After  R.  A.  F.  Penrose,  Geol.  Survey  of 

Ark..  1890,  Vol.  L,  p.  177. 


420  KEMP'S  ORE  DEPOSITS. 

is  secoDd  to  Crimora  in  production.  As  at  Crimora,  the  ores 
occur  in  pockets  in  stiff  clay,  and  are  associated  with  quartzite 
which  is  not  sharply  identified  as  yet.  It  may  be  Cambrian 
(Potsdam),  or  Upper  Silurian  (Medina).  West  of  Cartersville  is 
the  Cave  Spring  region,  where  the  ores  occur  with  Lower 
Silurian  cherts.  There  are  numerous  other  localities  not  yet 
of  commercial  importance  along  the    Appalachians,  in    Ten- 


FlG.  157. — The  Turner  mine,  BatesvUle  region,  Arkansas.     After  li.  A.  F. 
Penrose,  Geol.  Surveg  of  Ark.,  1890,  Vol.  I.,  p.  272. 

nessee  and  elsewhere.     Full  descriptions  will  be  found  in  Pen- 
rose's report,  cited  below. 

2.14.26.  Batesville,  Ark.  The  ore  is  braunite,  and  is  found 
in  masses  disseminated  in  a  residual  clay  which  was  thought  by 
Penrose  to  have  been  left  by  the  alteration  of  a  limestone  locally 
called  the  St.  Clair.  The  stratigraphy  has  been  revised  in 
some  important  particulars  by  H.  S.  Williams,  as  noted  below. 
The  St.  Clair  was  regarded  by  Penrose  as  of  geologic  age  be- 


TEE  LESSEE  METALS.  45^1 

tween  the  Trenton  and  Niagara  periods.  It  is  underlain  by 
another  limestone  called  the  Izard,  which  is  later  than  the  Cal- 
ciferous.  On  Penrose's  St.  Clair  a  series  of  cherts,  called  the 
Boone  cherts,  is  found,  which  are  of  Subcarboniferous  (Missis- 
sippian)  age.  The  clays  are  sometimes  in  valleys,  sometimes 
on  hillsides,  according  to  the  unequal  decay  of  the  limestone. 
South  of  the  Batesville  district  are  th6  Boston  Mountains,  a 
range  of  low  hills  500  feet  high,  and  from  these  the  manganifer- 
ous  rocks  form  a  low  monocline  to  the  north.  The  district  is 
in  northern  central  Arkansas.  The  ore  was  thought  by  Pen- 
rose to  have  been  derived  from  the  limestone,  and  to  have 
separated  in  its  decay.  H.  S.  Williams  has  modified  the  above 
stratigraphy  in  important  particulars  by  close  paleontological 
determinations  and  the  modifications  bear  on  the  origin  of  the 
ores  in  a  very  important  way,  changing  them,  as  regards  their 
original  home  from  deep-water  deposits  to  shallow-water  ones. 
Williams  observed  that  the  limestone,  called  the  St.  Clair  above, 
contained  both  a  Lower  Silurian  fauna  and  an  Upper  Silurian 
one.  In  one  good  exposure  on  the  Cason  property  they  were 
separated  by  a  thin  band  of  shale,  which  shale  contained  the 
manganese  ore,  Williams  therefore  restricts  the  name  St. 
Clair  limestone  to  the  Lower  Silurian  (or  Ordovician)  stratum, 
and  calls  the  shale  the  Cason  shale,  and  the  overlying  Upper 
Silurian  (or  Eo-Silurian)  limestone  the  Cason  limestone.  Some 
of  the  clay,  which  was  observed  by  Penrose  to  contain  the 
nodules  of  ore  has  resulted  from  this  shale,  and  it  may  be  that 
the  ore  generally  has  come  from  the  same  source.  The  geolog- 
ical relations  would  then  be  closely  parallel  with  Crimora,  Va. 
(H.  S.  Williams,  "Age  of  the  Manganese  Beds  of  the  Batesville 
Region  of  Arkansas,"  Amer.  Jour.  Set.,  October,  1894,  325.) 
2.14.27.  Southwestern  Arkansas  contains  a  second  district 
in  which  the  ore  occurs  in  a  great  stratum  of  novaculite  of 
probable  Lower  Silurian  age.  The  ores  are  of  no  practical  im- 
portance, being  too  lean  and  too  disseminated.  Small  amounts 
of  manganese  ore  have  been  obtained  in  California,  in  San 
Joaquin  County,  and  from  Red  Rock,  in  San  Francisco  harbor. 
The  former,  and  perhaps  others  in  the  State,  may  prove  impor- 
tant hereafter.  Penrose  has  described  an  interesting  deposit  of 
manganese  ore  near  Golconda,  Nev.  It  is  an  interbedded, 
lenticular  mass  about  150  feet  long  and  10  feet  thick  as  amaxi- 


422  KEMP'S  ORE  DEPOSITS. 

mum  in  calcareous  tufa,  of  Pleistocene  age.  It  is  remarkable 
fcr  its  content  of  2.78%  tungstic  acid.  Penrose  interprets 
it  as  a  superficial  deposit  from  uprising  springs,  whose 
waters  presumably  formed  a  pool,  allowing  of  the  oxidation 
and  precipitation  of  the  dissolved  manganese.  The  latter  was 
derived  from  lower  lying  rocks,  presumably  igneous,  although 
sediments  are  not  an  impossible  source.^  Leadville,  Colo., 
is  now  an  important  source  of  manganese  ores,  the  shipments 
going  as  far  as  Chicago.  The  geological  relations  are  the  same 
as  for  the  lead-silver  ores,  earlier  described. 

2.14.28.  Considerable  manganese  occurs  at  times  in 
some  of  the  Lake  Superior  iron  ores,  especially  those  from  the 
Gogebic  range.  Cuba  has  also  afforded  some  shipments 
notably  high  in  this  metal.  In  the  Santiago  region  the  ore 
forms  nodules  in  the  soil  from  which  it  is  obtained  by  stripping 
and  washing. 

2.14.29.  Quite  productive  deposits  are  found  in  pockets  at 
Markhamville,  Kings  County,  N.B.,  in  Lower  Carboniferous 
limestone.  Some  thousands  of  tons  have  been  shipped.  Other 
mines  are  situated  at  Quaco  Head.  At  Tenny  Cape,  in  the 
Bay  of  Minas,  Nova  Scotia,  is  another  deposit  in  Lower  Car- 
boniferous limestone,  which  has  furnished  several  thousand  tons 
of  ore.     Others  less  important  occur  on  Cape  Breton.^ 

^  R.  A.  F.  Penrose,  "A  Pleistocene  Manganese  Deposit,"  Jour.  ofGeol., 
I.,  275,  1893. 

^  "Manganese  Mines  near  Santiago,  Cuba,"  Eng.  and  Min.  Jour.,  No- 
vember 24, 1888,  p.  439.  H.  P.  Brumell,  "Notes  on  Manganese  in  Canada," 
Amer.  Geol.,  August,  1892,  p.  80.  D.  de  Cortazar,  "General  Review  of 
Occurrence  and  Manufacture,"  Reps,  and  Awards,  Group  L,  Centen. 
Exposition,  p.  196.  D.  T.  Day,  Mineral  Resources,  1883,  p.  424 ;  1883-84,  p. 
550.  F.  P.  Dunnington,  "On  the  Formation  of  the  Deposits  of  Oxides  of 
Manganese,"  Amer.  Jour.  Sci.,  iii.,  XXXVI.,  175.  Rec.  W.  M.  Fon- 
taine, "Crimora  Manganese  Deposits,"  The  Virginias,  March,  1883,  pp. 
44-46.  Rec.  C.  E.  Hall,  "Geological  Notes  on  the  Manganese  Ore  De- 
posits of  Crimora,  Va.,"  Trans.  Amer.  Inst.  Min.  Eng.,  June,  1891.  E. 
Halse,  "  Notes  on  the  Occurrence  of  Manganese  Ore,  near  Mulege,  Baja 
California,  Mexico,'  Trans.  N.  of  Eng.  Min.  and  Mech.  Eng.,  XLI.,  302, 
1892.  H.  Hoy,  "Ores  of  Manganese  and  their  Uses,"  Proc.  and  Trans.  N. 
S.  Inst.  Nat.  Sci.,  Halifax.  II.,  1864-65,  p.  139.  "  Manganese  Mining  in 
Merionethshire,  England,"  Eng.  and  Min.  Jour.,  December  18,  1886,  p. 
438.  R.  A.  F.  Penrose,  Ann.  Rep.  Ark  Geol.  Survey,  1890,  Vol.  I.  The 
best  work  published.  Rec.  "  Origin  of  the  Manganese  Ores  of  Northern 
Arkansas,'  etc.,  Amer.  Assoc.  Adv.  Sci.,  XXXIX.,  250.     "The  Chemical 


THE  LESSER  METALS.  423 

2.14.30.  Panama.  Manganese  ores  have  been  shipped 
In  large  quantities  from  the  mainland  of  South  America,  just 
east  of  the  base  of  the  Isthmus  of  Panama,  although  still  in  the 
province  of  that  name.  The  ores  occur  about  5  to  6  miles  from 
the  coast  and  8  miles  from  the  dock,  in  the  valley  of  the  Rio 
Viento  Frio.  Great  masses  of  the  oxides  of  manganese  (both 
braunite  and  pyrolusite)  occur  in  residual  clay.  More  or  less 
quartz  is  associated  with  them.  The  original  rock  seems  from 
the  very  decomposed  pieces  available  to  have  been  a  clastic 
one,  chiefly  of  feldspathic  fragments.  The  ores  are  rich  in  man- 
ganese and  low  in  phosphorus.  There  had  been  shipped  to  the 
close  of  189G,  18,215  tons.' 

Relation  of  Iron  and  Manganese  in  Sedimentary  Rocks,"  Jcmr.  of  Oeol., 
I.,  356,  1893.  J.  D.  Weeks,  Mineral  Resources  of  the  U.  S.,  1885,  p.  303 
(Rec);  1886,  p.  180;  1887,  p.  144.  D.  A.  Wells,  "  On  the  Distribution  of 
Manganese,"  ^mer.  Assoc.  Adv.  Sci.,  VI.,  275.  C.  L.  Whittle,  "Genesis 
of  the  Manganese  Deposits  at  Quaco,  N.  B,,"  Proc.  Bost.  Soc.  Nat.  Hist., 
XXV.,  p.  253. 

^  E.  J.  Chibas,  ' '  Manganese  Deposits  of  the  Department  of  Panama, 
Republic  of  Colombia,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXVII.,  63,  1897. 
"Railroad  Building  and  Manganese  Mining  in  Colombia."  Eng.  Mag., 
December,  1896,  Vol.  XII.,  426.  "Construction  of  a  Light  Mountain 
Railroad  in  the  Republic  of  Colombia,"  Trans.  Amer.  Soc.  Civ.  Eng., 
XXXVI.,  65,  1896. 


CHAPTER  XV. 

THE    LESSER     METALS,     CONTINUED — MERCURY,    NICKEL     ANI> 
COBALT,  PLATINUM,  TIN. 

MERCURY. 

2.15.01.  Ores:  CinDabar,  HgS.  Hg.  86.2,  S.  13.8.  Meta- 
cinnabarite  is  a  black  sulphide  of  mercury.  Native  mercury 
also  occurs.  Tiemannifce  the  selenide  HgSe,  and  onofrite  the 
sulphoselenide,  Hg(SeS)  have  been  met  at  Marysvale,  in  south- 
ern Utah.^ 

Mercury, usually  called  quicksilver  in  commerce,  has  been  dis- 
covered in  vs^orkable  quantities  at  a  number  of  places  along  the 
Pacific  coast  of  North  America.  Its  chief  localities  are  in  the 
Coast  ranges  of  California,  where,  though  formerly  more  pro- 
ductive, it  is  still  quite  largely  obtained.  The  deposits  extend 
into  Oregon,  but  are  of  no  great  importance.  In  small  amount 
it  has  been  mined  in  Nevada  and  Utah,  and  has  recently  been 
discovered  in  promising  although  not  demonstrated  quantity  in 
w^estern  Texas.  Many  localities  are  known  in  Mexico,  but 
Guadalcazar,  in  the  State  of  Guerrero,  and  Huitzuco,  in  San 
Luis  Potosi,  have  proved  most  productive.  In  South  America, 
the  mines  at  Huancavelica,  in  Peru,  have  been  in  the  past  of 
vast  productiveness.  In  Europe,  Almaden  in  Spain,  is  much 
the  most  important  of  all  the  deposits  known  to-day,  but  Idria 
in  Austria,  and  Avala  in  Servia  are  still  of  value.  Several 
other  well-known  mining  districts  of  former  years  have  lapsed 
into  inactivity.  In  Asia  the  great  deposits  of  Kwei-Chau  are 
described  as  being  of  great  possibilities. 

^  G.  J.  Brush  and  W.  J.  Comstock,  "American  Sulpho-selenides  of  Mer- 
cury, with  Analyses  of  Onofrite  from  Utah,"  Amer.  Jour.  Sci.,  April,  1881, 
312.  G.  F.  Becker  describes  this  as  Tiemannite,  Monograph  XIII.,  p, 
385,  U.  S.  Geol.  Survey,  ISSS;  Mineral  Resources,  1892-5;  Tenth  Census. 
XIII.,  463,  1880. 


THE  LESSEE  METALS,   CONTINUED.  425 

2.15.02.  In  their  geological  relations  the  ores  of  quicksilver 
are  quite  invariably  associated  with  igneous  rocks,  although 
the  walls  are  often  sedimentary. 

2.15.03.  G.  F.  Becker^  has  recently  given  an  admirable  re- 
view of  quicksilver  deposits,  the  world  over,  their  mineralogi- 
cal  associates  and  probable  methods  of  origin,  and  the  same 
subject  has  been  treated  by  A.  Schrauf.^  Becker  has  tabulated 
the  minerals  associated  with  cinnabar  from  twenty-eight  world- 
wide localities,  and  has  made  it  evident  that  silica,  either  as 
quartz  or  in  the  opaline  state,  and  calcite  are  the  common  gangue 
associates.  Pyrifce  or  marcasite  is  almost  invariably  present 
and  bitumen  is  very  widespread.  Various  other  antimony, 
arsenic,  silver,  lead,  copper  and  zinc  minerals,  as  well  as  gold, 
are  of  somewhat  irregular  occurrence.  Becker  reaffirms  his 
previously  cited  theory  of  origin,  that  the  cinnabar  has  come 
up  in  solution  as  a  double  sulphide  with  the  alkaline  sulphides, 
but  lays  stress  upon  the  precipitating  properties  of  bituminous 
substances,  which  reactions  were  corroborated  by  experiment. 
He  favors  the  view  that  the  cinnabar  has  impregnated  porous 
or  decomposed  rock,  rather  than  that  it  has  actually  replaced 
it  by  metasomatic  processes.  The  probable  source  of  the  ore 
in  deep-seated  and  widely-distributed  granitic  rocks,  and  espe- 
cially in  such  portions  as  overlie  the  foci  of  volcanic  activity  is 
affirmed , 

2.15.04.  Example  50.  New  Almaden.  Cinnabar  with  sub- 
ordinate native  mercury,  in  a  gangue  of  crystallized  and  chal- 
cedonic  quartz,  calcite,  dolomite,  and  magnesite,  forming  a 
stockwork,  or  * 'chambered  vein,"  in  shattered  metamorphic 
rocks  (pseudo-diabase,  pseudo-diorite,  serpentine  and  sand- 
stone). There  are  two  main  fissures,  making  a  sort  of  V,  with 
a  wedge  of  country  rock  between.  The  ore  bodies  are  in  the 
fissures  and  also  in  the  intervening  wedge.  They  are  associated 
with  much  attrition  clay.  A  great  dike  of  rhyolite  runs 
nearly  parallel  to  the  fissures,  and  to  this  Becker  attributes  the 
activity  of  circulations  which  filled  the  vein.  The  uprising 
solutions  have  often  been  influenced  by  the  seams  of  clay  and 

*  G.  F.  Becker,  "Quicksilver  Ore  Deposits,  with  Statistical  Tables," 
Mineral  Resources  of  the  United  States,  1892. 

'A,  Schrauf,  "  Aphorismen  ueber  Zinnoher, "  Zeits.  fiir  prakt.  GeoL, 
January,  1894,  p.  10. 


426 


KEMP'S  ORE  DEPOSITS. 


appear  to  have  especially  deposited  the  ore  along  the  lower 
sides  of  them.  The  ore  has  found  a  lodgment  in  the  crevices 
of  all  sorts  on  the  general  line  of  disturbance,  and  has  im- 
pregnated porous  rocks,  when  they  occurred  in  its  course.  It 
has  been  deposited  simultaneously  with  the  various  gangue 
minerals.  The  wall  rocks  are  of  Neocomian  (Early  Cretaceous) 
age,  but  have  suffered  extreme  metamorphism.  Long  after 
this  ceased  came  the  intrusion  of  the  rhyolite,  and  probably 
the  formation  of  the  fissures  now  holding  the  ore.  The  intro- 
duction of  the  ore  was  in  either  Pliocene  or  post-Pliocene  time, 
certainly  not  earlier.  Several  other  mines,  of  which  the  Enri- 
quita  and   Guadalupe  are    most    important,   are  near   New 


Fig.  158. — Section  of  the  Great  Western  cinnabar  mine.     After  G.  F. 
Becker,  Monograph  XIIL,  U.  8.  Ueol.  Survey,  p.  360. 

Almaden,  but  the  New  Almaden  is  much  the  largest  of  all  the 
North  American  deposits  yet  developed.  New  Idria  is  farther 
south,  high  up  toward  the  summit  of  the  Coast  range.  The 
ore  is  deposited  in  shattered  metamorphic  rocks  of  Neocomian 
(Lower  Cretaceous)  age,  and  in  overlying  Chico  beds.  The 
ore  is  accompanied  by  bitumen.  Basalt  is  abundant  ten  miles 
away.  North  of  San  Francisco  other  mines  have  been  opened, 
among  which  are  the  Oat  Hill,  Great  Eastern,  and  Great 
Western.  The  mines  are  in  a  region  pierced  by  eruptions  of 
basalt  and  andesite,  which  doubtless  gave  impetus  to  the  ore- 
bearing  solutions.  The  ores  are  deposited  in  both  metamorphic 
and  unaltered  sedimentary  rocks. 


I 


THE  LESSER  METALS,   CONTINUED.  4>Z1 

2.15.05.  Example  50a.  Sulphur  Bank.  This  is  in  the 
same  general  region  as  the  last,  but  from  its  peculiar  character 
has  been  one  of  the  best  known  of  ore  deposits.  A  great  flow 
of  basalt  has  come  down  to  the  shores  of  Clear  Lake  from  the 
west,  Waters  charged  with  alkaline  (including  ammonia) 
carbonates,  chlorides,  berates,  and  sulphides,  and  with  CO2, 
H2S,  SO2,  and  marsh  gas,  have  circulated  through  it.  Sul- 
phur and  sulphuric  acid  have  formed  at  the  surface,  and  the 
latter  has  dissolved  the  bases  of  the  rock,  leaving  pure  white 
silica  behind.  Lower  down,  cinnabar  is  found,  both  in  the 
basalt  and  in  the  underlying  sedimentary  rocks,  with  other  sul- 
phides and  chalcedony.  Le  Conte  attributed  its  precipitation  to 
cold  surface  waters,  charged  with  sulphuric  acid,  which 
trickled  down  and  met  the  hot  alkaline  solutions.  Becker 
refers  the  same  to  the  ammonia  set  free  toward  the  surface  by 
diminished  heat  and  pressure.  The  California  cinnabar  de- 
posits have  been  often,  but  wrongly,  referred  to  vapors  of  the 
sulphide  volatilized  by  internal  heat  and  condensed  above. 

2.15.06.  Example  506.  Steamboat  Springs,  Nev.  These 
springs  are  in  Nevada,  only  six  miles  from  the  Comstock 
Lode.  Granite  is  the  principal  rock,  while  on  it  lie  metamor- 
phic  varieties  of  the  Jura-Trias,  and  much  andesite  and  basalt. 
Issuing  through  small  fissures,  the  hot  springs  deposit  chal- 
cedony in  some  places,  carbonates  in  others,  and  cinnabar  as 
well  as  gold.  The  following  minerals  have  been  noted  :  "Sul- 
phides of  arsenic  and  antimony;  sulphides  or  sulphosalts  of 
silver,  lead,  copper,  and  zinc;  oxide  and  possibly  sulphide  of 
iron;  manganese,  nickel  and  cobalt  compounds,  and  a  variety 
of  the  earthy  minerals'*  (Becker).  Becker  thinks  the  source  of 
the  cinnabar  is  in  all  cases  in  the  underlying  granite,  and 
that  it  has  come  up  in  solution  with  sodium  sulphide,  and  has 
been  precipitated  toward  the  surface  bj'  the  other  compounds 
in  the  hot  alkaline  waters,  with  which  it  would  remain  in 
solution  at  greater  depths,  temperatures  and  pressures.  The 
Steamboat  Springs  are  often  and  properly  cited  as  metallifer- 
ous veins  in  active  process  of  formation.^ 

*  W.  P.  Blake,  "  Quicksilver  Mine  at  Almaden,  Cal.,"  Amer.  Jour.  Sci., 
a..  XVII.,  438.  G.  F.  Becker,  "Quicksilver  Deposits  of  the  Pacific  Slope," 
Monograph  XIIL,  U.  S.  Geol.  Survey,  Chap.  17.  Rec.  "On  New  Alma 
den,"  Cal.  Oeol.  Survey,  I.,  p.  68.     S.  D.  Christy,  "On  the  Genesis  of  Cin 


428  KEMP'S  ORE  DEPOSITS. 

2.15.07.  Cinnabar  has  recently  been  reported  by  W.  P. 
Blake  from  southwestern  Texas,  in  a  rough,  broken  and  almost 
uninhabited  district  some  10  to  12  miles  from  the  Rio  Grande 
River.  The  cinnabar  occurs  "in  massive  limestone  and  in  a  sili- 
ceous shale,  and  a  white  earthy  clay-like  rock,  and  in  part  in  a 
true  breccia  of  grayish,  white,  siliceous  shale,  dense  and  com- 
pact, imbedded  and  cemented  in  a  red  and  chocolate-colored  fer- 
ruginous mass,  also  dense  and  hard.'*  The  age  of  the  nearest 
determinable  beds  is  Lower  Cretaceous.  The  quicksilver  ore 
seems  to  impregnate  the  beds,  and  also  to  lie  along  a  shattered  or 
brecciated  belt.  It  is  oftentimes  in  concentric  layers  with  oxide 
of  iron,  with  which  it  seems  to  have  in  general  a  common 
origin,  but  to  have  been  laid  down  in  intervals  of  changed  con- 
ditions of  deposition.  In  addition  to  the  disseminated  granules, 
there  are  bunches  of  soft,  friable  cinnabar  in  the  shales, 
limestones  and  breccia.  It  is  undemonstrated  as  yet,  whether 
the  deposits  are  workable  or  not.  The  conditions  are  some- 
what hard  because  water  is  lacking,  and  the  location  is  remote.^ 

NICKEL   AND  COBALT. 

2.15.08.  These  two  metals  almost  always  occur  together.*^ 

nabar  Deposits."  Amer.  Jour.  Set.,  June,  1878,  p.  453;  Eng.  and  Min. 
Jour.,  August  2,  1879,  p.  65.  D.  de  Cortazar,  "General  Review  of  Occur- 
rence, etc.,  of  Mercury,"  Reps,  and  Awards,  Group  I.,  Centennial  Exposi- 
tion, p.  196.  William  Irelan,  Ann.  Reps.  Cal.  State  Mineralogist.  Laur, 
"On  Steamboat  Springs,"  Annates  des  Mines,  1863,  423.  J.  Le  Conte  and 
Rising,  "Metalliferous  Vein  Formation  at  Sulphur  Bank,"  J.mer.  Jour. 
Sci.,  July,  1882;  Eng.  and  Min.  Jour.,  August  26,  1882,  p.  109.  J. 
Le  Conte,  "On  Steamboat  Springs,"  Amer.  Jour.  Sci.,  June,  1883,  p.  424. 
"Genesis  of  Metalliferous  Veins,"  Idem,  July,  1883.  J.  A.  Phillips, 
"On  Sulphur  Bank,  California,"  Phil.  Mag.,  1871,  p.  401;  Quar.  Jour. 
Geol.  Sci.,  XXXV.,  1879,  p.  390.  Rolland,  Annates  des  Mines,  XIV.. 
384,  1878.  B.  Silliman,  "Notes  on  the  New  Almaden  Quicksilver  Mines," 
Amer.  Jour.  Sci.,  ii.,  XXXVII.,  190.  Siveking,  B.  und  H.  Zeitung,  1876, 
p.  45. 

*  W.  P.  Blake,  "Cinnabar  in  Texps,"  Trans.  Amer.  Inst.  Min.  Eng.^ 
XXV.,  68. 

^  The  following  general  papers  on  nickel  and  cobalt  are  important :  F. 
D.  Adams,  "On  the  Igneous  Origin  of  Certain  Ore  Deposits,"  Oen.  Min. 
Assoc.  Prov.  Quebec,  January  12,  1894.  P.  Argall,  "Nickel:  The  Occur- 
rence, Geological  Distribution  and  Genesis  of  its  Ore  Deposits,"  Proc.  Col. 
Sci.  Soc,  December  4,  1893.  W.  L.  Austin,  "Nickel:  Historical  Sketch," 
Idem,  same  date.    H.  B.  v.  Foullon,  "  Ueber  einige  Nickelerzvorkommen,"" 


THE  LESSER  METALS,   CONTINUED.  429 

Their  ores  embrace  the  following  general  classes:  (1)  Com- 
pounds with  arsenic  and  rarely  with  antimony,  or  with  arsenic 
(or  antimony)  and  sulphur;  (2)  Sulphur  compounds,  including 
nickeliferous  pyrrhotite  and  pyrite;  (3)  Oxidized  ores,  mostly 
hydrated  silicates  related  to  serpentine.^  .Although  the  num- 
ber of  minerals  involving  nickel  and  cobalt  is  quite  large,  the 
ores,  properly  speaking,  are  comparativelj^  few ;  nickeliferous 
pyrrhotite  is  much  the  most  important,  especially  as  concerns 
this  country,  but  the  oxidized  ores  may  yet  prove  serious. 
Only  the  ores  {i.e.,  minerals  commercially  important)  are  men- 
tioned in  the  table  below. 

Niccolite NiAs,                              Ni.44.06  As.  55. 94 

Millerite  ........  NiS,                                 Ni.  64. 83  S.    35. 17 

Linnaeite (00^)384      Co.21.34,  Ni.30.53    Fe.  3.37      S.   41.54 

Pentlandite . . . .  (NiFe)  S,  Ni.34.23    Fe.30.25      S.    33.42 

Genthite 2NiO,2MgO,Si02,6HgO.  Ni.22.6. 

Garnierite H20(Ni,Mg)O.Si02+iH20  Ni.25.0. 

Zaratite NiC03,2Ni(OH)  2+4H80    Ni.46.8. 

To  these  nickeliferous  pyrrhotite  and  pyrite  should  be  added, 
i;he  former  being  the  most  important  of  all. 

2.1 5.09.  Niccolite  was  reported  years  ago  at  Tilt  Cove,  New- 
foundland, in  some  quantity,  but  elsewhere  has  not  been  found 
in  any  serious  amount  in  North  America.  It  also  occurs  in 
some  of  the  western  openings  of  the  Sudbury  district.  Millerite 
furnished  a  small  portion  of  the  nickel  at  the  Gap  Mine,  Penn- 
sylvania, as  noted  below.  Linnseite,  variety  siegeuite,  occurs  in 
a  sandstone  bed  at  Mine  la  Motte  in  disseminated  octahedra, 
and  although  small  attempts  have  been  made  to  utilize  it,  the 
amounts  are,  so  far  as  known,  not  large  enough  for  success. 
Pentlandite  must  be  mentioned  together  with  nickeliferous 
pyrrhotite.  It  has  been  somewhat  of  a  question  among  min- 
eralogists in  just  what  relations  the  nickel  ocqurs  in  pyrrhotite; 

Jahrbuchd.  k.  k.  geol.  Reichsanstalt,  Vienna,  XLIL,  223,  1892.  D.  Levat, 
Annalesdes  Mines,  1892,  Part  II.  J.  H.  L.  Vpgt,  "  Nikkelforkoraster  og 
Nikkelproduktion  "  (Occurrence  and  Production  of  Nickel),  Norwegian 
Geol.  Survey,  Kristiania,  1892;  a  resume  in  German  accompanies  the 
paper.  "Sulphidische  Ausscheidungen  von  Nickelsulphiderzen,"  etc., 
Zeits.  fur  prakt.  Geol,  April,  1893,  125. 

^  This  is  practically  the  same  grouping  that  is  given  by  J.  H.  L.  Vogt, 
Zeits.  filr  prakt.  Geol,  April,  1893,  125.  See  also  P.  Argall,  Proc.  Colo. 
Sci.  Soc,  December  4,  1894. 


430  KEMP'S  CRE  DEPOSITS. 

whether  replacing  the  iron  in  FeTSg,  or  some  other  variety  of 
FenSn+i,  to  the  extent  of  a  fraction  of  one  per  cent,  up  to  five, 
or  whether  there  is  an  isomorphous  or  distinct  nickel  or  iron- 
nickel  sulphide  intermingled  with  the  pyrrhotite.  As  far  back 
as  1843  Scheerer  identified  pentlandite  from  southern  Norway, 
and  several  other  related  minerals,  such  as  polydymite,  have 
been  less  definitely  described.  More  recently  it  has  been  shown 
that  the  nickel-rich  portions  of  the  pyrrhotitic  ores  are  quite 
feebly  magnetic, and  processes  have  even  been  suggested  for  con- 
centrating the  nickel  based  on  this  principle.^  Pentlandite  is 
non-magnetic,  and  possibly  this  mineral  in  very  fine  dissemina- 
tions may  contribute  of  its  richer  percentage  of  nickel  to  raise 
the  total  of  the  pyrrhotites  as  mined.  Some  nickel,  however, 
always  remains  in  the  strongly  magnetic  residues,  so  that  we 
are  not  yet  justified  in  abandoning  the  earlier  view  that  this 
metal  replaces  some  of  the  iron  of  the  pyrrhotite.  Pyrrhotite 
is  the  chief  ore  at  Sudbury,  and  was  the  ore  at  the  Gap  Mine, 
Pennsylvania,  until  the  workings  were  dismantled  in  1894. 
In  southeast  Missouri,  but  more  especially  at  Mine  la  Motte, 
nickeliferous  pyrite  accompanies  the  galena  (see  2.05.09),  and 
has  furnished  a  considerable  amount  as  a  by-product  in  the 
metallurgy  of  lead.  Of  the  oxidized  ores  it  is  not  easy  to  speak 
as  regards  their  individual  importance.  The  hydrated  silicates 
are  of  extremely  variable  composition,  and  while  one  or  two 
illustrations  of  the  type  are  selected  for  the  table,  no  one  of 
them  is  yet  seriously  mined  in  America. 

2.15.10.  Example  16c.  (See  2.03.16  and  2.04.02.)  Pyr- 
rhotite Beds  or  Veins.  Lenticular  masses  of  pyrrhotite 
inter  bedded  in  gneisses  and  schists  as  described  for  pyrite 
They  are  known  at  various  places  in  the  East.  Openings  have 
been  made  at  Lowell,  Mass.,  Chatham  and  Torringtou,  Conn., 
and  on  the  mountain  on  the  east  bank  of  the  Hudson,  called 
Anthonj^'s  Nose.^    The  last  is  much  the  largest  of  those  named, 

^  See  in  this  connection  D.  H.  Browne,  "On  the  Sudbury  Ores,  "  Eng. 
and  Min.  Jour.,  December  2,  1893.  Eec.  S.  H.  Emmens,  "The  Consti- 
tution of  Nickeliferous  Pyrrhotite,"  Jour.  Amer.  Chem.  Soc,  XIV.,  No.  10. 

'  H.  Credner,  Berg,  und  Huett.  Zeit.,  1866,  p  17.  Dana's  Treatise  on 
Mineralogy,  6th  Edition,  under  Pyrrhotite,  gives  several  analyses  from 
Putnam  County,  N.  Y.  J.  F.  Kemp,  "  The  Nickel  Mine  at  Lancaster  Gap, 
Penn.,  and  the  Pyrrhotite  Deposits  at  Anthony's  Nose,  on  the  Hudson," 
Trans.  Amer.  Inst.  Min.  Eng.,  XXIV.,  620  and  883. 


THE  LESSER  METALS,   CONTINUED.  431 

and  though  never  mined  for  the  nickel  which  is  known  to  be 
present,  it  was  utilized  as  a  material  for  sulphuric  acid  fumes 
during  the  ten  years  succeeding  1865.  The  geological  relations 
give  it  especial  interest.  The  ore  body  is  entirely  analogous  to 
the  magnetite  lenses,  which  are  not  rare  in  the  Highlands  of 
the  Hudson.  It  lies  in  a  light-colored  gneiss,  conformably  to 
the  laminations,  and  must  have  attained  20  or  30  feet  in  thick- 
ness. It  has  been  mined  down  300  or  400  feet,  and  apparently 
for  50  feet  or  more  on  the  strike.  About  100  yards  west  is 
found  a  basic  gneiss,  consisting  of  green  hornblende  and 
plagioclase,  with  a  little  biotite.  The  wall  rock  contains 
quartz,  plagioclase  and  very  subordinate  hornblende.  In  the 
thin  section  it  appears  fully  as  acidic  as  a  quartz-diorite. 

Much  hornblende  is  associated  with  the  pyrrhotite,  and  occa- 
sional lumps  of  magnetite,  with  which  are  found  titanite  and 
apatite.  The  ore  jnelded  about  28%  sulphur  as  used  for  years 
in  the  chemical  works,  and  was  especially  prized  because  it 
contained  no  trace  of  arsenic.  The  geological  relations  give  no 
reason  for  regarding  the  ore  body  as  a  basic  segregation  of  a  gab- 
broic  magma,  but  quite  the  contrary.  Several  of  the  magne- 
tite mines  in  this  region,  it  may  be  added,  are  troubled  with 
pyrrhotite  in  the  ore,  but  whether  it  is  nickeliferous  has  not 
been  determined.^ 

Similar  pyrrhotites,  low  in  nickel,  occur  in  Ontario.*^ 
2.15.11.  Example  13a.  Gap  Mine,  Penn. ;  Sudbury,  Ont. 
Bodies  of  nickeliferous  pyrrhotite  and  chalcopyrite  with  verj' 
subordinate  pyrite,  in  the  outer  portions  of  intrusions  of  basic 
igneous  rocks,  which  may  be  metamorphosed  to  amphibolites. 
Cobalt  is  present  in  less  amount  than  nickel  and  varies  much 
in  its  relative  proportions.  Secondary  millerite  sometimes 
forms  in  cracks,  as  do  quartz,  siderite  and  one  or  two  other 
minerals,  but  in  variety  of  species  ore  bodies  of  this  type  are 
exceptionally  barren.  The  type  is  of  world-wide  distribution, 
as  noted  by  Vogt,  and  is  well  known  in  Norway,  Sweden  and 
one  or  two  other  European   localities.     The  number  of  the  Ex- 

^  W.  H.  Hoffman,  "  The  late  Discovery  of  Large  Quantities  of  Magnetic 
and  Non-magnetic  Pyrites  in  the  Croton  Magnetic  Iron  Mines,  N.  Y.," 
Trans.  Amer.  Inst.  Min.  Eng.,  June,  1892.  J.  C.  Smock,  Bulletin  of  New 
York  State  Museum,  Dunderberg  Mine,  p.  18;   Hobby  Opening,  p.  24. 

^  F.  D.  Adams,  Geol  Survey  Canada,  Vol.  VI.,  1891-93,  Part  J. 


432  KEMP'S  ORE  DEPOSITS. 

ample  indicates  its  genetic  parallelism  with  the  titaniferous 
magnetites  of  2.03.11. 

2.15.12.  The  Gap  Mine,  in  Lancaster  County,  southeast- 
ern Pennsylvania  ,^  was  originally  opened  for  copper  in  the  pre- 
ceding century.  The  copper  enterprises  were  all  failures,  and 
not  until  in  the  fifties  was  the  presence  of  nickel  recognized. 
The  mine  then  became  the  largest  single  producer  of  its  day, 
and  remained  active  until  1893,  since  which  time  it  has  been 
abandoned.  As  shown  in  the  accompanying  map  and  sections 
a  lenticular  outcrop  or  mass  of  greenish  black  rock,  about 
2,000  feet  in  length  and  500  feet  as  a  maximum  width,  is  found 
in  the  midst  of  mica  schist,,  and  apparently  conformable  to  the 
laminations.  It  strikes  nearly  east  and  west,  and  is  contracted 
along  the  section  A  A,  where  it  was  most  productive.  It 
seemed  to  pinch  in  somewhat  in  depth,  so  far  as  the  workings 
extended  (about  250  feet).  The  ore  was  chiefly  found  at  the 
eastern  end  of  the  lense,  and  was  much  less  abundant  where 
followed  to  the  westward  on  the  south  side  with  a  drift,  as  far 
as  is  colored  black.  Prospect  holes  still  further  west  proved 
the  presence  of  the  amphibolite,  but  failed  to  show  ore.  A 
dike  of  olivine-diabase  of  the  familiar  Triassic  sort  common  in 
southeastern  Pennsylvania  outcrops  about  1,500  feet  southeast, 
but  it  is  much  later  in  time  than  the  amphibolite,  with  which 
and  with  the  ore  it  has  no  apparent  connection.  The  ore  is 
pyrrhotite  in  far  the  largest  amount,  but  when  cut  in  thin  sec- 
tions along  with  the  containing  amphibolite,  it  is  seen  under 
the  microscope  that  a  light  yellow- mineral,  presumably  pyrite, 
is  mixed  all  through  the  bronze-colored  pyrrhotite.  The  ore  is 
richest  near  the  contact  and  fades  into  lean  disseminations  as 
this  is  left.  The  lense  consists  in  far  the  largest  part  of  green 
hornblende  of  the  common  variety,  quite  pale  in  thin  section, 
and  with  pleochroism  from  green  to  yellow.  Many  specimens 
are  formed  of  this  and  nothing  else,  except  scattered  grains  of 

'  P.  Fraser,  "Report  CCC,"  SecoM  Penn.  Geol.  Survey.  A  geological 
description  and  historical  sketch  are  given,  and  also  an  outline  map  in  the 
accompanying  atlas,  on  which  the  figure  here  used  is  based.  The  descrip- 
tion, however,  gives  the  impression  that  the  ore  is  millerite,  and  hardly 
mentions  pyrrhotite,  whereas  the  millerite  is  a  comparatively  rare  min- 
eral. Joseph  Wharton,  "Analysis  of  the(^Nickel  Ore  from  the  Gap  Mine, 
Lancaster  County,  Penn.,"  Pi^oc.  Phila.  Acad.  Sei.,  1870,  p.  6. 


434  KEMP'S  ORE  DEPOSITS, 

pyrrhotite.  Others  show  a  little  plagioclase,  and  a  few  flakes  of 
biotite.  Recognizable  remains  of  orthorhombic  pyroxene  and 
olivine  were  detected  despite  the  general  and  thorough  meta- 
morphisni  of  the  rock.  No  more  accurate  name  can  be  given 
it  than  amphibolite,  although  there  is  little  doubt  that  it  origi- 
nally was  a  very  basic  gabbro  or  pyroxenite.  The  ore  contains 
considerable  secondary  millerite,  which  forms  crusts  on  the 
cracks  of  pyrrhotite,  and  often  veins  and  stringers  of  quartz 
traverse  it.  In  vuggs  in  these,  beautiful  crystals  of  vivianite 
are  rarely  met.  The  close  parallel  that  the  ore  body  affords  in 
its  geology  to  several  Norwegian  mines  figured  by  Vogt  in  the 
Zeitschrift  fiir  prakt.  Geologie,  April,  1893,  Plates  V.  and 
VI.,  is  very  striking.  (See  especially  Meinkjar  Grubenfeld, 
Fig.  3  of  Plate  VI.)  The  views  of  Vogt  on  the  origin  of  such 
ore  bodies  by  differentiation  of  a  basic  igneous  magma  in  cool- 
ing, and  by  concentration  of  the  early  crystallizations  at  the 
contacts,  according  to  Soret's  principle,  were  outlined  earlier 
in  the  discussion  of  the  table  of  classification  of  ore  deposits. 
In  a  metamorphosed  rock,  such  as  the  Gap  amphibolite,  there  is 
a  reasonable  ground  for  regarding  the  ore  as  a  contact  deposit 
due  to  deposition  from  solutions,  but  after  seeing  the  larger, 
less  metamorphosed  but  otherwise  closely  analogous  ore  bodies 
of  the  Sudbury  district,  the  writer  (J.  F.  Kemp)  sees  no  escape 
from  the  conclusion  that  they  and  it  are  original  crystalliza- 
tions from  the  igneous  magma  as  much  as  any  other  component 
minerals  of  the  intruded  mass.^ 

2.15.13.  The  Sudbury  nickel  mines  are  of  quite  recent  de- 
velopment, as  they  were  opened  in  1886,  although  discovered 
earlier.  They  are  situated  forty  miles  north  of  Georgian  Bay, 
an  arm  of  Lake  Huron,  and  on  the  eastern  portion  of  the  original 
Huronian  belt.  The  Laurentian  granites  and  gneisses,  which 
to  the  east  form  a  vast,  monotonous  stretch  of  low  glaciated  hil- 
locks and  swamps,  are  covered  near  Sudbury,  and  for  a  hundred 
miles  west,  by  a  great  area  of  later  Huronian  sediments  (gray- 

*  Literature  on  the  Gap  Mine,  W.  P.  Blake,  Mineral  Resources,  1882,  p. 
399.  J.  Eyerman,  "  Mineralogy  of  Pennsylvania, "  P.  Fraser,  Report  CCC, 
Second  Penn.  Oeol.  Survey,  p.  163.  J.  F.  Kemp,  "The  Nickel  Mine  at 
Lancaster  Gap,  Penn. ,  and  the  Pyrrhotite  Deposits  at  Anthony's  Nose,  on 
the  Hudson,"  Trans.  Amer.  Inst.  Min.  Eng.,  XXIV.,  620,  883,  1884.  J. 
Wharton,  "Analysis  of  Nickel  Ore  from  the  Gap  Mine,'  Proc.  Phila 
Acad.  Sci.,  1870,  p.  6. 


THE  LESSEE  METALS,  CONTINUED, 


435 


iv^ackee,  quartzites,  schists)  and  by  immense  intrusions  and  dikes 
of  norites  and  more  acid  rocks,  at  times  more  or  less  metamor- 
phosed; emptive  breccias  and  otiier  interesting  varieties  too 
numerous  to  cite  in  detail  are  also  present.    The  geology  is  veiry 


by  swamps  and 
however, 
sorite  ran 

One  on  die 


436  KEMP'S  ORE  DEPOSITS. 

has  along  its  own  southeastern  side  some  rich  deposits,  includ- 
ing the  Evans,  Copper  Cliff,  Stobie  and  Blezard.  The  Evans 
is  on  a  small  outlier  from  the  main  mass,  and  the  Stobie  and 
Blezard  are  further  in  from  the  actual  contact  than  is  the  Cop- 
per Cliff.  Some  miles  west  of  the  great  diorite  dike  just 
referred  to  is  the  large  Murray  mine  in  another  intrusion,  with 
a  stretch  of  supposed  Laurentian  granite  between.  Some 
twenty  miles  southwest,  and  in  connection  with  a  still  differ- 
ent diorite  dike  are  found  the  Worthington  mine  and  several 
undeveloped  openings  in  Drury  and  Denison  townships. 
About  the  same  distance  northwest  of  Sudbury  is  a  region 
around  Wahnapitae  Lake,  well  thought  of,  but  not  yet  produc- 
tive. 

2.15.14.  In  a  recent  valuable  paper^  T.  L.  Walker  has 
traced  out  the  petrographical  character  of  the  basic  intrusives 
that  contain  the  ore.  In  crossing  the  dikes,  the  rock  in  its 
unmetamorphosed  condition  remote  from  the  contacts  is  a 
norite.  As  the  edge  and  therefore  the  ore  body  are  approached, 
the  hypersthene  changes  to  bastite,  and  finally  in  the  mines  to 
hornblende,  which  has  occasioned  the  use  of  the  name  diorite. 
Titan  if  erous  magnetite  accompanies  the  ore,  and  has  been 
observed  enclosed  in  it.'  Walker  concludes  that  the  sulphides 
have  crystallized  directly  from  the  fused  magma,  just  as  have 
the  usual  components  of  an  igneous  rock.  It  would  seem  that 
the  change  of  hypersthene  to  hornblende  at  the  borders  would 
indicate  some  considerable  metamorphism  apparently  dynamic 
in  its  nature. 

2.15.15.  The  ore  bodies  betra}^  their  presence  by  great  out- 
crops of  rusty  gossan,  consisting  of  limonit^  in  layers  and  cellu- 
lar masses,  which  have  resulted 'from  the  decay  of  the  pyrrhotite 
and  chaloopyrite.  The  outcrop  of  this  gossan  may  run  with 
local  interruptions  for  long  distances.  '  When  it  was  penetrated 
in  the  early  prospecting  the  chalcopyrite  lying  below  attracted 
attention,  and  the  deposits  were  regarded  as  copper  mines. 
Later  the  presence  of  the  nickel  in  the  pyrrhotite  wsts  recog- 
nized, and  the  nickel  became  the  principal  object.  The  two 
ores  are  inseparably  intermingled  and  themselves  form  irregular 
masses  often  of  great  size  in  the. diorite.     It  is  stated  by  Peters 

*  T.  L.  Walker,  "  Geological  and  Petrographical  Studies  of  the  Sudbury 
Nickel  District,  Canada,"  Quar.  Jour,  of  the  Geol.  Soc,  1897,  40. 


Fias.  161  AND  1Q2.—View  of  the  Copper  Cliff  Mine,  near  Sudbury,  Ontario. 

The  mine  is  in  diorite.     The  ridge  at  the  background  is  granite. 

From  photographs  by  T.  G.  White,  1894. 


THE  LESSER  METALS,   CONTINUED.  437 

that  the  early  work  at  the  Stobie  showed  ore  over  100  feet 
across.  The  diorite  is  a  dense  black  rock  resembliog  most 
closely  black  basalt  in  its  appearance.  Quite  pure  pieces  of 
sulphides  of  large  size  are  at  times  obtained,  but  practically  all 
the  ore  contains  rock  up  to  30%  or  more  of  its  weight,  and  the 
sulphides  form  irregular  masses  in  it.  Great  heaps  of  rock  too 
lean  to  work,  but  showing  bits  of  sulphides  through  the  pieces, 
are  thrown  out  on  the  dumps.  The  workings  are  in  the  form 
both  of  open  cuts  and  of  shafts,  from  which  the  drifts  wander 
out  somewhat  irregularly  in  search  of  the  ore-masses.  While 
it  is  truly  said  the  ores  favor  the  contacts,  this  should  not  be 
too  closely  interpreted.  The  mines  and  the  gossan  do  lie  along 
the  outer  portions  of  the  diorite  masses,  yet  as  now  mined  at 
all  the  large  producers  they  are  entirely  in  the  diorite,  and  often 
very  considerable  distances  from  the  actual  contact,  of  which 
no  evidence  appears  from  the  workings.  Included  masses  of 
granite  occur  with  the  ore  at  Copper  Cliff,  and  as  a  general 
thing  have  a  rim  of  chalcopyrite.  Some  small,  secondary  and 
insignificant  quartz  veins  ramify  through  the  diorite,  and  con- 
tain chalcopyrite  and  some  pyrrhotite,  both  of  which  are 
secondary,  but  they  are  trifling  in  amount.  On  the  contrary, 
the  masses  of  the  sulphides  are  irregularly  distributed,  often  as 
small  isolated  bits,  throughout  the  fresh,  dense  diorite,  and  leave 
one  no  reasonable  alternative  but  to  conclude  that  they  are  as 
much  an  original  crystallization  from  the  igneous  magma  as 
any  other  of  the  minerals  in  the  rock.  Evidence  of  disturb- 
ance has  been  found  in  the  region,  and  apparent  fault  lines  are 
not  lacking,  but  the  great  open  cuts  of  the  mines  show  no 
evidence  of  them.  The  method  of  igneous  origin  has  been 
somewhat  attacked.  Posepny,  for  example,  refers  to  it  as 
something  extraordinary  when  in  his  great  essay  on  **The 
Genesis  of  Ore-Deposits,"  he  cites  Vogt's  work,  and  controverts 
it  strongly ;  but  it  appears  to  the  writer,  after  having  seen  the 
mines,  that  no  process  of  solution  and  replacement  can  be  con- 
ceived of  as  introducing  these  scattered  masses  of  sulphides 
into  dense,  undecomposed  and  apparently  unbroken  igneous 
rock,  which  would  not  strain  the  faith  of  a  conservative  ob- 
server to  a  far  greater  degree.^ 

^  D.  H.  Browne  gives  in  the  School  of  Mines  Quarterly  for  July,  1895  p. 
297,  a  very  suggestive  paper  on  "  Segregation  in  Ores  and  Mattes."    The 


438  KEMP'S  ORE  DEPOSITS. 

2.15.16.  It  is  an  interesting  fact  that  sperrylite,  the  unique 
arsenide  of  platinum,  occurs  in  the  Sudbury  region,  but  was 
not  first  discovered  in  a  nickel  mine.  Traces  are,  however, 
said  to  occur  in  the  nickel  ores.  Cobalt  is  in  comparatively 
small  amount,  much  less  than  in  some  other  nickel  regions. 
The  ores  vary  in  richness  in  different  mines  and  in  different 
parts  of  the  same  mine.  They  run  from  over  1%  to  over  b% 
nickel,  and  have  a  copper  percentage  somewhat  under  the 
nickel.  The  Worthington  has  yielded  a  little  gersdorffite 
(NiAsS),  and  niccolite  (NiAs)  in  secondary  quartz  veins,  and 
a  vein  is  reported  from  Denison  township  containing  both 
these.  A  galena  vein  is  reported  from  the  same  region,  and  a 
little  millerite  is  said  to  have  been  found  in  the  Copper  Cliff 
mine.  Traces  of  zincblende  have  also  been  noted  in  some  of  the 
ores,  but  aside  from  these  the  mineralogy  is  limited  to  the  two 
principal  sulphides.^ 

2.15.17.  Example  49a.  Riddle's,  Douglass  County,  Ore- 
gon. Irregular  deposits  of  hydrated  silicates  of  nickel  and 
magnesia,  in  serpentine  formed  by  the  alteration  of  peridotites 
or  related  rocks.  Limonite,  chalcedonic  quartz  and  chromite 
are  quite  invariable  associates,  as  are  clays  and  other  products 

results  of  a  long  experience  with  mattes  show  that  in  the  matte  pot  the 
copper  tends  to  collect  at  the  top  and  sides,  the  nickel  in  the  center. 
Parallels  are  drawn  with  the  ore  bodies,  in  the  central  parts  of  which  the 
nickel  is  in  excess  of  the  copper,  while  at  the  edges  the  copper  exceeds 
the  nickel. 

1  On  Sudbury  see  F.  D.  Adams,  "The  Igneous  Origin  of  certain  Ore 
Deposits/'  General  Min.  Assoc,  Prov.  Quebec,  January  12,  1894,  A,  E, 
Barlow,  "The  Nickel  and  Copper  Deposits  of  Sudbury,  Ont.,"  Ottawa 
Naturalist,  June.  1891.  R.  Bell,  Geol.  Survey  of  Can.,  1890-91;  F.  5,  91, 
Bull.  Geol.  Soc.  Amer.,  II.,  p,  125.  T.  G.  Bonney,  "Notes  on  a  part  of  the 
Huronian  Series  near  Sudbury,"  Quar.  Jour.  Geol.  Soc,  XLIV,,  32,  1888. 

D.  N,  Browne,  Eng.  and  Min.  Jour.,  September  16  and  December  2,  1893. 

E.  R.  Bush,  "The  Sudbury  Nickel  Region,"  Idem,  March  17,  1894,  p.  245. 

F.  W,  Clarke  and  C.  Catlett,  "  Platiniferous  Nickel  Ore  from  Canada," 
A7ner.  Jour.  Sci.,  iii.,-  XXXVII.,  372.  J.  IJ.  Collins,  "Note  on  the  Sud- 
bury Copper  Deposits,"  Quar.  Jour.  Geol.  Soc,  XLIV.,  834,  J,  Garnier, 
"  Mines  du  Nickel,  Cuivre  et  Platine,  du  District  du  Sudbury,"  ilfemozres 
de  la  Societie  des  Ingenieurs  Civils.,  Paris,  March,  1891.  W.  H,  Merritt, 
Trans.  Amer.  Inst.  Min.  Eng.,  XVII.,  295.  E,  D,  Peters,  "On  Sudbury 
Ore  Deposits,"  Idem,  October,  1889;  Eng.  and  Min.  Jour.,  October  26,- 
1889.  Berg.  u.  Huett.  Zeit.,  L.,  149, 1891,  Mineral  Resources  of  the  U.  S.. 
1888,  110. 


THE  LESSER  METALS,   CONTINUED.  439 

of  alteration.  The  ore  occurs  in  loose  boulders  on  the  surface, 
and  as  a  coating  on  the  walls  of  small  cracks  and  vein  lets  that 
penetrate  the  more  massive  serpentine.  The  largest  deposits 
of  this  character,  so  far  as  yet  opened  in  this  country,  are  in 
the  Coast  range,  southwest  of  Riddle's  Station,  Douglass 
County,  Oregon,  on  the  Oregon  and  California  Railroad. 
The  mines  occur  on  a  steep  hillside,  in  serpentine  that  has  re- 
sulted from  the  alteration  of  the  variety  of  peridotite,  called 
harzburgite,  i.e.,  bronzite  and  olivine.  Open  cuts,  small  drifts 
and  test  pits  have  served  to  show  the  nickel  silicates,  richest  at 
the  outcrop  and  fading  out  into  small  veinlets  and  reticulations 
in  depth,  until  beyond  the  zone  of  superficial  decay,  they  disap- 
pear. The  openings  are  still  in  the  condition  of  prospects,  and 
productive  mining  is  yet  to  be  begun.  The  nickel  has  been 
shown  by  J.  S.  Diller  to  have  been  derived  from  the  olivine 
of  the  rock,  as  chemical  analysis  of  this  mineral  indicated 
0.26%  NiO  By  the  familiar  and  ready  alteration  of  the  oliv- 
ine the  nickel  has  separated  as  the  silicate,  and  has  finally 
been  concentrated  sufficiently  to  be  noticeable.^  At  Webster, 
in  North  Carolina,  are  surface  deposits  of  nickel  silicate  which 
have  attracted  attention.  They  occur  in  the  variety  of  perido- 
tite, which  is  chiefly  olivine,  and  is  called  dunite.  The  geo- 
logical relations  and  origin  are  practically  the  same  as  those 
in  Oregon,  just  cited.  The  mines  are  not  yet  producers.^ 
Green  crusts  of  oxidized  nickel  compounds  have  been  found 
with  the  chromite  in  the  town  of  Texas,  Penn.,  but  are  of  no 
practical  importance.  Such  superficial  discolorations  are  very 
common  in  serpentinous  districts,  but  it  is  a  curious  fact  that 
they  are  notably  lacking  in  the  dioritic  varieties  of  ExamplelSa. 
The  greatest  deposits  in  serpentines  are  found  in  New  Cale- 
donia, in  the  South  Pacific,  where  they  have  been  mined  for 
some  years  past,  and  have  furnished  in  the  last  decade  the 
largest  part  of  the  world's  supply.     The  ores  occur,  as  is  the 

^  F.  W.  Clarke  and  J.  S.  Diller,  "Nickel  Ores  from  Riddle's,  Webster 
and  New  Caledonia,"  Amer.  Jour.  Set.,  iii.,  XXXV.,  483.  H.  B.  v.  FouUon, 
"On  Riddle's,"  Jahr.  d.  k.  k.  Geol.  Reichsanstalt,  1893,  224.     Rec. 

2  Clarke  and  Diller,  as  cited  in  preceding  reference.  S.  H.  Emmens, 
•'The  Nickel  Deposits  of  North  Carolina,"  Eng.  and  Min.  Jour.,  April  30, 
1892,  p.  476.  H.  Wurtz,  "On  the  Occurrence  of  Cobalt  and  Nickel  in 
Gaston  County,  North  CaroUna,"  Amer.  Assoc.  Adv.  Set.,  XII.,  221;  Amer. 
Jour.  Sci.,  ii.,  XXVII.,  24. 


440  KEMP'S  ORE  DEPOSITS. 

usual  case,  associated  with  serpeotine,  and   along  the  contact 
of  the  serpentine  with  overlying  beds  of  red  clay/ 

2.15.18.  Example  23a.  Mine  la  Motte.  Considerable 
pyrite  occurs  with  the  lead  ores  mentioned  under  Example  23, 
and  is  separated  in  the  ore-dressing  and  treated  by  itself,  as  it 
contains  nickel  and  cobalt.  Such  pyrite  is  most  abundant  at 
Mine  la  Motte,  and  considerable  matte  is  made  and  shipped 
abroad.  Siegenite,  a  variety  of  linnseite,  is  also  found  im- 
pregnating a  bed  of  Cambrian  sandstone  that  underlies  the 
lead-bearing  dolomite.  It  is  not  abundant  enough  to  be  of 
practical  importance.^ 

2.15.19.  Nickel  ores  have  also  been  reported  from  Salina 
County,  Arkansas.^  Millerite  occurs  in  a  vein  with  quartz 
gangue  in  black  shales.  It  is  not  practically  productive. 
Nickel  is  also  reported  in  a  rather  fine  conglomerate  from 
Logaji  County,  Kansas.  It  occurs  with  manganese  and 
limonite  in  the  cementing  material  of  the  rock.*  Oxidized 
nickel  ores  have  also  been  reported  at  the  Lovelock  mines, 
Cburchill  Countj-,  Nevada,  which  passed  in  depth  into  sul- 
phides.^ Although  they  were  originally  regarded  as  promising, 
they  have  not  proved  a  productive  source  as  yet.  At  the  Gem 
mine,  Colorado,  sulphide  ores  have  also  been  produced.  Millerite 
occurs  as  an  interesting  mineral  in  many  other  places  (St. 
Louis,  Mo. ;  with  red  hematite  in  Jefferson  County,  New  York, 
etc.),  but  is  only  a  rarity.  Its  interesting  position  at  the  former 
locality,  in  hair-like  tufts  in  the  midst  of  geodes  indicates  that 

*  F.  Benoit,  "  Etude  sur  les  Mines  de  Nickel  de  la  Nouvelle  Caledonie," 
Bull,  delas  Societe  de  I'lnd.  Minerals,  VI.,  753,  1892.  J.  Garnier,  "  Me- 
moire  sur  les  Gisements  de  Cobalt,  de  Chrome  et  de  Fer  a  la  Nouvelle 
Caledonie,"  »Soc.  des  Ingenieurs  Civils.,  1887.  S.  Heard,  Jr.,  "New  Cale- 
donia Nickel  and  Cobalt,"  Eng.  and  Min.  Jour.,  August  11,  1888,  p.  103. 
D.  Levat,  Assoc.  Frangaise  pour  VAdvanc.  des  Sci.,  Paris,  1887.  L. 
Pelaton,  "Carte  Geologique  de  la  Nouvelle  Caledonie,"  Genie  civile,  1891. 

'  J.  M.  Neill,  "Notes  on  the  Treatment  of  Nickel  and  Cobalt  Mattes  at 
Mine  la  Motte,"  Trans.  Amer.  Inst.  Min.  Eng.,  XIII  ,  634.  For  additional 
literature  see  under  2.05.09. 

3  Ark.  Geol.  Survey,  1888,  Vol.  I.,  pp.  34,  35. 

*  F.  P.  Dewey,  "  On  the  Nickel  Ores  of  Russell  Springs,  Logan  County, 
Kansas,"    Trans.   Amer.   Inst.   Min.   Eng.,  XVII.,  636. 

*  A.  v.  Hodges,  "  Notes  on  the  Occurrence  of  Nickel  and  Cobalt  Ores  in 
Nevada,"  Trans.  Amer.  Inst.  Min.  Eng.,  X.,  657.  S.  B.  Newberry,  "  Nickel 
Ores  from  Nevada,"  Amer.  Jour.  Sci.,  iii.,  XXVIII.,  123. 


THE  LESSEE  METALS,   CONTINUED.  441 

nickeliferous  solutions  must  have  circulated  rather  widely  in 
these  limestones.  In  Jefferson  County  it  probably  resulted 
from  the  decaying  pyritous  mineral  to  which  Smyth  refers  the 
iron  ore,  as  outlined  earlier. 

PLATINUM. 

2.15.'^0.  Some  hundreds  of  ounces  of  platinum  are  annually 
gathered  from  placer  washings  in  northern  California,  and  two 
or  three  times  as  much  more  from  British  Columbia.  Much 
iridium  and  osmium  are  associated  with  it.  In  October,  1889, 
F.  L.  Sperry,  the  chemist  of  the  Canadian  Copper  Company, 
of  Sudbury,  discovered  a  heavy  crystalline  powder  in  the  con- 
centrates of  a  small  gold-quartz  mine  in  the  district  of  Algoma. 
He  detected  the  presence  of  platinum,  and  sent  the  material  to 
Professors  Wells  and  Pen  field,  of  Yale,  by  whom  it  was  ana- 
lyzed and  crystallographically  determined  to  be  the  arsenide 
of  platinum,  PtAs2,  the  first  compound  of  platinum,  other  than 
an  alloy,  detected  in  nature.  It  has  been  appropriately  named 
sperrylite  by  Wells,  and  although  not  at  present  a  source  of 
platinum,  it  may  merit  attention,  as  the  price  of  the  metal  has 
sometimes  approximated  that  of  gold.  The  chief  reliance  of  the 
world  for  platinum  is  Eussia,  whose  deposits  are  in  the  Urals. 
More  or  less  comes  also  from  Colombia,  South  America,  and 
from  placer  washings  elsewhere.  Serpentine  is  very  generally 
its  mother-rock.^ 

TIN. 

2.15.21.  Ores:  Cassiterite,  SnO^,  Sn.  78.67,  O.  21.33.  The 
sulphide  stannite  is  a  rather  rare  mineral. 

'  California:  Eng.  and  Min.  Jour.,  June  29,  1889,  587.  B.  Silliman, 
"  Cherokee  Gold  Washings,  California,"  Amer.  Jour.  Sci.,  iii.,  VI.,  132. 
Canada:  F.  W.  Clarke  and  Ch.  Catlett,  "  Platiniferous  Nickel  Ore  from 
Canada,"  Amer.  Jour.  Sci,  iii.,  XXXVII.,  372.  H.  L.  Wells  and  S.  L. 
Penfield,  "Sperrylite,  a  New  Mineral,"  Idem,  iii.,  XXXVII.,  67.  Russia: 
A.  Daubree,  "On  the  Platiniferous  Rocks  of  the  Urals,"  Trans.  French 
Acad.  Sci.,  March,  1875;  Amer.  Jour.  Sci.,  iii.,  IX.,  470.  General  paper 
by  C.  Bullman,  The  Mineral  Industry  for  1882,  p.  373.     Rec. 

"^  An  elaborate  review  of  the  tin  mines  of  the  world  by  C.  M.  Roelker 
will  be  found  in  the  XVI.  Ann.  Rep.  of  the  Director  of  the  U.  S.  Geol. 
Survey,  Part  III.,  pp.  458-538,  1895.  E.  Reyer  has  given  a  general  dis- 
cussion in  "Zinn,  einegeologisch-montanistisch-historische  Monographic, " 
Berlin,  1881.  A  general,  genetic  discussion  is  given  by  J.  H.  L.  Vogt, 
"Die  Zinnstein  gang-gruppe,"  Zeits.  fiir prakt.  Geol.,  1895,  145. 


442  KEMP'S  ORE  DEPOSITS. 

Cassiterite  occurs  in  small  stringers  and  veins  on  the  borders 
of  granite  knobs  or  bosses,  either  in  the  granite  itself  or  in  the 
adjacent  rocks,  in  such  relations,  that  it  is  doubtless  the  result 
of  fumarole  action  consequent  on  the  intrusion  of  the  granite. 
It  appears  that  the  tin  oxide  has  probably  been  formed  from 
the  fluoride.  A  favorite  rock  for  the  ore  is  the  so-called 
greisen,  a  mixture  of  quartz  and  muscovite  or  lithia  mica,  and 
probably  an  original  granite  altered  by  fumarole  action. 
Topaz,  tourmaline,  and  fluorite  are  found  with  the  cassiterite, 
and  indicate  fluoric  and  boracic  fumaroles.  Wolframite,  schee- 
lite,  zinnwaldite  and  one  or  two  other  minerals  are  character- 
istic associates.  Cassiterite  seems  also  to  crystallize  out  of  a 
granite  magma  with  the  other  component  minerals.     Cassite- 


FlG.  1^.— Horizontal  section  of  the  Etta  granitic  knob.  Black  HiUs,  8.  D, 
After  W.  P.  Blake.  Mineral  liesouvces,  1884,  p.  603. 

rite,  being  a  very  heavy  mineral,  accumulates  in  stream 
gravels,  like  placer  gold,  affording  thus  the  stream  tin.  When 
of  concentric  structure  the  ore  is  called  wood  tin.  It  is  not  yet 
demonstrated  that  the  United  States  have  workable  tm  mines. 

2.15.22.  Example  51.  Black  Hills.  Cassiterite  disseminated 
in  masses  of  albite  and  mica  and  associated  with  immense 
crystals  of  spodumene,  which  are  contained  in  knobs  of  granitic 
rock.  Columbite,  tantalite,  and  beryl  are  also  found.  There 
are  two  granite  knobs  which  are  best  known,  the  Etta  and  the 
Ingersoll.  The  former  is  a  conical  hill,  which  pierces  mica  and 
garnetiferous  slates  and  which  is  250  feet  high  by  150  feet  by 
200  feet.     Tunnels  show  it  to  have  a  concentric  structure — first. 


THE  LESSER  METALS,   CONTINUED.  443 

a  zone  of  mica;  second,  a  zone  of  great  spodumene  crystals, 
with  an  albitic,  so-called  greisen  which  carries  cassiterite  in 
its  interstices;  lastly,  a  mixture  of  quartz  and  feldspar  as  a  core. 
Other  tin-bearing  granites  occur  as  dikes,  or  veins,  as  much  as 
80  feet  wide,  and  bearing  the  so-called  greisen  and  tin  ore  in 
quartz.  They  are  called  segregated  veins  by  Carpenter,  who 
doubts  their  true  igneous  character,  probably  on  good  ground. 
No  tin  is  yet  commercially  produced.  The  tin  deposits  extend 
also  into  Wyoming.^ 

2.15.23.  Pebbles  of  stream  tin  have  been  found  in  gold 
washings  in  Montana  and  Idaho.  Tin  is  also  known  in  the 
Temescal  Mountains,  southern  California.  The  area  has  re- 
cently been  described  by  H.  W.  Fairbanks,  who  summarizes 
the  geological  relations  as  follows :  "A  semi-circular  area  of 
granite,  over  two  miles  in  diameter,  surrounded  on  the  north- 
west and  south  by  porphyries,  and  joined  on  the  east  to  a  great 
body  of  granitic  rocks  extending  indefinitely  in  that  direction. 
Around  the  border  of  this  granite  protuberance  are  many  dikes 
of  a  fine-grained  granite.  Cutting  through  the  granite  in  a 
northeast  and  southwest  direction  are  black  tourmaline  veins, 
which  form  the  gangue  of  the  tin  ore  when  it  is  present.*' 
While  tourmaline  is  a  common  associate  of  tin  ores,  this  great 
abundance  of  it  is  unusual.  The  ore  occurs  as  a  yellow,  un- 
crystalline  variety,  in  layers,  and  as  a  brown,  granular,  mas- 
sive form,  or  in  brown  crystals.  The  ore  and  veinstone  seem 
to  have  replaced  the  usual  minerals  of  the  granite,  doubtless  by 
fumarole  action  along  fissures.  The  mining  proved  unsuccess- 
ful  after  a  serious  attempt.^ -^ 

^  W.  P.  Blake,  Mineral  Resources,  1883-84,  p.  602,  Rec.  Amer.  Jour. 
Set,  September,  1883,  p.  335;  Eng.  and  Min.  Jour.,  September  8,  1886. 
"Tin  Ore  Deposits  of  the  Black  Hills,"  Trans.  Amer.  Inst.  Min.  Eng., 
XIII.,  691.  F.  R.  Carpenter,  Prelim.  Rep.  Dak.  School  of  Mines,"  1888; 
also  Trans.  Amer.  Inst.  Min.  Eng.,  XVII.,  570.  "  Tin  in  the  Black  Hills," 
Eng.  and  Min.  Jour. ,  November  28,  1884,  p.  353.  Mineral  Resources  of 
the  U.  S.,  annually  under  "Tin."  W.  P.  Headden,  "Notes  on  the  Dis- 
covery and  Occurrence  of  Tin  Ore  in  the  Black  Hills,"  Colo.  Sci.  Soc, 
III.,  347.  A.  J.  Morse,  "Harney  Peak  Tin  Mines,"  Eng.  and  Min.  Jour., 
November  17,  1894,  p.  463. 

"^  W.  P.  Blake,  "  Occurrence  of  Wood  Tin  in  California,  Idaho,  and  Mon- 
tana," Min.  and  Sci.  Press,  San  Francisco,  August  5,  1882.  H.  W.  Fair- 
banks, "The  Temescal  Tin  Distnct,"  Eleventh  Rep.  Cal.  State  Mineral- 
ogist, 1893,  pp.  111-114.  A  fuller  paper  will  be  found  in  the  Amer.  Jour. 
-Sci.,  July,  1897,  39.    H.  G.  Hanks,  Rep.  Cal.  State  Mineralogist,  1884,  p.  121. 


444  KEMP'S  ORE  DEPOSITS. 

2.15.24.  Narrow  veins  carrying  cassiterite  have  been  ex- 
ploited in  the  granite  and  schistose  rocks  of  Rockbridge  and 
Nelson  counties,  Virginia,  in  North  Carolina,  and  in  Alabama. 
Companies  have  been  formed  to  work  the  two  former,  but  as 
yet  without  a  notable  output.^ 

2.15.25.  Cassiterite  has  been  discovered  in  narrow  veins  in 
mica  schists  with  lepidolite  and  fluorite  at  Winslow,  Me.,  and 
is  known  at  other  places  in  Maine  and  New  ,  Hampshire.  A 
salted  tin  prospect  several  years  ago  spread  the  impression  that 
tin  was  to  be  found  in  Missouri.^ 

Narrow  quartz  veins  have  been  recently  discovered  near  El 
Paso,  Tex.,  with  cassiterite  richly  disseminated  through  them. 

2.15.26.  Mexico.  Tin  ores  occur  in  a  great  number  of 
places  in  Mexico,  and  small  amounts  of  tin  have  been  pro- 
duced during  and  since  the  time  of  the  Aztecs.  W.  R.  Ingalls 
has  carefully  described  the  deposits  in  the  State  of  Durango, 
and  has  shown  that  those  at  Potrillos  are  in  veinlets  or  small 
veins  in  rhyolitic  tuffs,  with  associated  topaz,  chalcedony  and 
hyalite.  The  cassiterite  is  in  irregular  bunches  and  nodules, 
but  as  in  practically  all  the  Mexican  mines,  the  amount  is  too 
small  to  be  the  basis  of  extended  mining.  Alluvial  gravels 
were  earlier  worked  but  have  been  long  since  exhausted.  At 
Cacaria,  likewise  in  Durango,  the  wall  rock  is  described  as 
quartz- porphyry,  but  near  the  city  of  Durango,  and  at  Sain 
Alto,  Zacatecas,  the  rhyolite  tuffs  are  again  the  country  rock.^ 
The  tin  of  Durango  runs  high  in  antimony. 


'  H.  D.  Campbell,  "  Tin  Ore,  jpassiterlte,  in  the  Blue  Ridge  in  Virginia." 
The  Virginias,  October,  1883^.  A.  R.  Ledoux,  "Tin  in  North  Carolina.' 
Eng.  and  Min.  Jour.,  December  14,  1889,  p.  521;  see  also  February,  1887, 
p.  111.  McCreath  and  Piatt,  Bull.  Iron  and  Steel  Assoc,  November  7, 
1883,  p.  209.  W.  Robertson,  London  Min.  Jour.,  October  18,  1884.  A. 
Winslow,  "Tin  Ore  in  Virginia,"  Eng.  and  Min.  Jour.,  NovembDr,  1885. 
Rec. 

""  W.  P.  Blake,  Mineral  Resources,  1884,  p.  538.  C.  H.  Hitchcock, 
"Discovery  of  Tin  Ore  and  Emery  at  Winslow,  Me.,"  Eyiq.  and  Min. 
Jour.,  October  2,  1880,  p.  218.  T.  S.  Hunt,  "Remarks  on  the  Occurrence 
of  Tin  Ore  at  Winslow,  Me.,"  Trans.  Amer.  Inst.  Min.  Eng.,  I..  573.  C.  T. 
Jackson,  "Tin  Ore  at  Winslow,  Me.,"  Proc.  Bost.  Soc.  Nat.  Hist.,  XII.,  267. 

'  F.  A.  Genth,  "On  the  Cacaria  Ores,"  Proc.  Amer.  Philo.  Soc,  XXTV., 
1887,  p.  23.     W.  R.  Ingalls,  "The  Tin  Deposits  of  Durango,"  Trans.  Amer. 
Inst.  Min.  Eng.,  XXV.,  146.     C.  W.  Kempton,  "Note  on  Tin  Ores  at  Sain 
Alto,  Zacatecas,"  Idem,  997. 


CHAPTER  XVL 

CONCLUDING  REMAEKS. 

2.16.01.  In  review  of  the  western  border  of  the  country,  we 
note  the  elevated  plateau  rising  from  the  Mississippi  to  the 
Rocky  Mountain  system,  which  consists  of  various  ranges  of 
general  north  and  south  or  northwest  and  southeast  trend,  with 
broad  valleys  between.  To  the  west  the  Colorado  Plateau  is 
met,  and  then  the  Wasatch  Mountains  and  the  Great  Basin,  with 
its  various,  subordinate,  north  and  south  ranges.  These  are 
succeeded  by  the  Sierra  Nevada,  and  the  great  valley  of  Cali- 
fornia, the  Coast  range,  and  finally  the  Pacific  Ocean. 

From  the  Archean  to  the  close  of  the  Carboniferous  there 
were  granitic  islands  around  which  active  sedimentation  pro- 
ceeded. At  the  close  of  the  Carboniferous  the  elevation  of  the 
Wasatch  and  the  region  of  eastern  Nevada  occurred.  At  the 
close  of  the  Jurassic  the  elevation  of  the  Sierra  Nevada  took 
place.  The  chief  upheaval  of  the  Rocky  Mountain  system 
came  at  the  close  of  the  Cretaceous  and  that  of  the  Coast  range 
at  the  close  of  the  Miocene  Tertiary.  Smaller  and  less  impor- 
tant oscillations  have  occurred  before  and  since.  Each  eleva- 
tion was  accompanied  by  foldings,  faultings,  and  extensive 
outpourings  of  eruptive  rocks.  The  resultant  fractures  and 
the  circulation  of  hot  and  chemically  active  solutions,  occasioned 
by  the  dying  volcanic  activity,  constitute  the  primary  cause  of 
the  formation  of  the  ore  deposits,  which  in  some  cases  lie  in 
ranges  along  the  lines  of  faulting  or  of  disturbances,  and  in 
others  are  irregularly  scattered.  We  may  recognize  the  Coast 
range  belt  with  mercury  and  chromium;  the  California  gold 
belt  in  the  western  Sierras;  the  silver  belt  of  Utah  on  the  west- 
ern flank  of  the  Wasatch;  a  belt  in  Arizona  from  southeast  to 
northwest,    along  the    contact   between   Paleozoic   limestone, 


446  KEMP'S  ORE  DEPOSITS. 

mostly  CarboDiferous,  and  the  Archean ;  and  the  great  strt  icb 
of  lead-silver  mines  in  the  Carboniferous  limestones  of  Colo- 
rado. The  other  areas  are  scattered,  and  apparently  exhibit 
no  such  grand  general  relations  to  these  geographical  and  geo- 
logical phenomena.^ 

2.16.02.  In  the  Mississippi  Valley,  W.  P.  Jenney  has  re- 
marked the  connection  of  the  antimony  and  silver  deposits  of 
Arkansas  with  the  Ouachita  uplift  that  traverses  that  State 
and  Indian  Territory;  the  location  of  the  Missouri  lead  and 
zinc  ores  along  the  Ozark  uplift;  and  he  has  referred  the 
Wisconsin  lead  and  zinc  mines,  as  well  as  those  in  the  neigh- 
boring parts  of  Iowa  and  Illinois,  to  an  uplift  south  of  the 
Archean  area  of  Wisconsin.  The  limitation  of  the  Lake 
Superior  copper  deposits  to  the  Keweenawan  system  may  be 
mentioned,  and  such  parallelism  as  prevails  among  the  Lake 
Superior  iron  ores.  In  the  East  the  great  belt  of  Clinton  ores; 
the  long  succession  of  Siluro-Cambrian  limonites  in  the  Great 
Valley;  the  black-band  ores  and  clay- ironstones  of  the  Carbon- 
iferous; the  closely  similar  geological  relations  of  non-titan  if  er- 
ous,  magnetite  lenses  in  the  Archean  gneisses;  and  the  general 
association  of  titaniferous  magnetites  with  rocks  of  the  gabbro 
family  the  country  over — all  are  striking  illustrations  of  broad, 
general  geological  features  that  may  characterize  extended 
series  of  ore  deposits.  To  these  may  be  appended  the  great 
series  of  pyritous  veins  in  the  slates  and  schists  of  the  East,  the 
gold  belt  of  the  Southeastern  States,  and  the  small  copper  de- 
posits associated  with  the  Triassic  traps  and  sandstones.  Aside 
from  the  groups  mentioned,  while  there  are  important  mines 
not  included  in  the  list,  the  others  do  not  exhibit  the  same  wide- 
spread uniformities  of  structure  or  associations.^    Yet,  from  the 

»  G.  F.  Becker,  Amer.  Jour.  Sci.,  Third  Series,  Vol.  XXIII.,  1884,  p. 
209.  W.  P.  Blake,  Rep.  Cal.  State  Board  of  Agriculture,  1866.  S.  F. 
Emmons,  "  The  Structural  Relations  of  Ore  Deposits,"  Trans.  Amer.  Inst. 
Min.  Eng.,  XVI.,  804.  R.  W.  Raymond,  "Geographical  Distribution  of 
Mining  Districts  in  the  United  States,"  Idem,  I.,  33.  Fortieth  Parallel 
Survey,  Vol.  III.,  Chapter  I.     "  Precious  Metals,"  Tenth  Census,  Vol.  XII. 

■^  It  is  only  proper  in  this  connection  to  refer  to  the  paper  by  T.  F.  Van 
Wagenen,  on  "System  in  the  Location  of  Mining  Districts,"  School  of 
Mines  Quarterly,  January,  1898,  p.  189.  The  author  regards  the  location 
of  the  veins  and  the  mining  districts  as  having  been  determined  by  the 
lines  of  terrestrial,  magnetic  currents,  which  converge  at  the  magnetic 


CONCLUDING  REMARKS.  447 

list  cited,  it  forcibly  appears  tbat  similar  conditions  have 
brought  about  related  ore  bodies  over  great  stretches  of  country ; 
and  while  in  the  opening  schemes  of  classification  points  of 
difference  were  emphasized,  in  the  closing  pages  points  of  re- 
semblance may  be  with  equal  right  brought  to  the  foreground. 
2.16.03.  A  few  general  conclusions  suggest  themselves  from 
the  preceding  pages. 

(1)  The  extreme  irregularity  in  the  shape  of  metalliferous 
deposits,  and  from  this  the  unwisdom  of  the  United  States  law 
in  the  West,  which  is  based  on  well-defined  fissure  veins. 
The  only  practicable  method  is  that  a  man  should  own  all  that 
is  embraced  in  his  property  lines,  whether  the  ore  body  out- 
crops outside  or  not.  "A  square  location  is  the  square  thing" 
(Raymond). 

(2)  The  very  general  proximity  of  eruptive  rocks  in  some 
form  to  the  ore  bodies.  Except  in  the  case  of  iron,  there  are 
only  a  few  where  these  are  not  present,  and  apparently  strong 
factors  in  the  circulations  which  formed  the  ore.  The  lead  and 
zinc  deposits  of  eastern  and  western  Missouri  and  the  neighbor- 
ing States,  and  of  New  York  and  Virginia,  are  almost  the  only 
ones,  and  we  are  justified  in  concluding  that  eruptive  rocks  are 
of  great  importance. 

(3)  We  know  from  the  investigations  of  Sandberger  and 
others  that  the  dark  silicates  of  many  rocks  contain  percentages 
of  the  common  metals.  The  choice  is  open  whether  to  refer  the 
ore  to  original  disseminations  in  these,  and  to  derive  it  by 
gradual  concentration,  probably  at  great  depths,  or  to  some 
indefinite  unknown  source,  which  can  only  be  described  as 
*^  below." 

pole  of  the  earth.  They  therefore  are  independent  of  the  great  lines  of 
mountain  making  and  igneous  outbreaks.  The  latter  are,  however,  re- 
garded by  the  present  writer  as  of  paramount  importance.  See  above 
paragraph. 


APPENDIX   I. 

In  the  following  pages  the  principal  schemes  of  classification 
of  ore  deposits  are  grouped  according  to  certain  relationships 
and  similarities  that  run  through  them.  It  would  be  interest- 
ing to  arrange  them  in  chronological  order,  but  points  of  like- 
ness and  unlikeness  would  not  thus  be  brought  out,  nor  can  the 
influence  of  one  writer  on  another  be  so  clearly  emphasized. 
The  underlying  object,  aside  from  showing  in  a  bird's-eye  view 
what  has  been  done,  is  to  lead  up  to  the  purely  genetic  class- 
ification which  appears  in  Chapter  VI,  Part  I.,  and  which 
would  properly  come  in  after  No.  16.  In  the  earlier  editions 
of  the  book  it  was  so  placed,  and  all  the  schemes  formed  part 
of  Chapter  VI,  but  so  many  have  appeared  in  later  years  that 
it  has  seemed  wiser  not  to  overload  the  main  text  with  matter 
that  is  largely  a  subject  of  reference,  and  that  can  be  treated 
with  greater  freedom  in  an  appendix.  The  importance  of  the 
genetic  principle  has  been  more  and  more  appreciated  in  recent 
years,  and  it  is  a  striking  fact  that  the  more  weighty  recent 
contributions  on  ore  deposits  have  been  dominated  by  it. 

In  reading  this  appendix  it  should  be  further  appreciated  that 
the  schemes  were  originally  grouped  so  as  to  lead  up  to  the  one 
on  page  56  as  a  climax,  and  that  in  it  mere  form  is  eliminated  to 
the  last  degree,  and  well-recognized  geological  phenomena  are 
brought  to  the  foreground.  It  has  indeed  been  said  with  force 
that  the  origin  of  ore  deposits  is  a  subject  which  is  very  largely 
a  matter  of  hypothesis,  and  that  it  involves  profound  subter- 
ranean causes,  of  which  we  know  but  little.  Still,  it  is  held 
that  an  acquaintance  with  what  has  been  accomplished  in  re- 
cent years  by  our  best  workers,  and  a  rigid  adherence  to  well- 
recognized  principles  in  geology  and  mineralogy,  especially  as 
developed  in  rock  study  {i.e.,  in  that  department  of  geology 
that   of  late  years  we  have  grown    to    call  petrology),    will 


APPENDIX  I.  449 

establish  much  that  cannot  be  questioned,  and  will  aid  in 
differentiating  the  cases  which  are  still  objects  of  reasonable 
doubt.  It  is,  however,  true  that  among  the  subjects  on  which 
human  imagination,  often  superstitious,  has  run  to  wild  ex- 
tremes, and  on  which  cranky  dreamers  have  exercised  their 
wits,  the  origin  of  ore  deposits  stands  out  in  particularly  strong 
relief. 

A.  Schemes  Involving  only  the  Classification  of  VeinSo 

(1) 

G.  A.  von  Weissenbach.^     Gangstudien,  1850,  p.  12. 
(a)  Sedimentargange  (Sedimentary  Veins). 
(6)  Kontritionsgange  (Attrition  Veins), 
(c)  Stalactitische   oder  Infiltrationsgange    (Stalactitic   or 

Infiltration  Veins). 
{d)  Plutonische  oder  Gebirgsmassengange  (Masses,  dikes, 

knobs,  bosses,  etc.,  not  necessarily  with  ores). 

(e)  Ausscheidungsgange  (Segregated  Veins)c 

(f)  Erzgange  (True  or  Fissure  Veins). 

(2) 

B.  von  Cotta,  in  comments  on  Von  Weissenbach's  Scheme. 

Gangstudien,  1850,    p.  79.     According  to  the  vein 
filling. 

1.  Gesteinsgange  (Dikes). 

{a)  Not  crystalline  (Sandstone). 
(6)  Crystalline  (Granite). 

2.  Mineralgange  (Veins). 

(a)  Of  one  non-metallic  mineral. 
ip)  Of  several  non-metallic  minerals. 

3.  Erzgange.     Ore  veins. 

(3) 

Bo  von  Cotta,  Idem,  p.  80.    According  to  Shape  and  Position. 
I.  Wahre,  einfache  Spalteogange  (Fissures), 
(a)  Querdurchsetzende  (Cross  fissures). 
{h)  Lagergauge  (Bed  veins), 
(c)  Kliifte  (Cracks),  Adern  (VeinletB). 


»  See  also  Whitney's  Metallic  Wealth  of  tlve  U.  S.,  1854,  p.  44. 


450  KEMP'S  ORE  DEPOSITS. 

II.  Gangziige  (Linked  Veins)/ 

III.  Netzgange  (Reticulated  Veins). 

IV.  Contaktgange  (Contact  Veins). 
V.  Lenticulargange  (Lenses). 

VI.  Stockformige  Gange  (Stocks,  Masses). 

(4) 

B.  von  Cotta,  Idem,  p.  80.     According  to  the  texture  of  the 
vein  filling. 
I.  Dichte  Gauge  {Compact  Veins). 
II.  Krystallinische  Gauge. 

III.  Krystallinisch,  koruige  (granular)  Gauge. 

IV.  Krystallinisch,  massige  (massive)  Gauge. 
V.  Gauge  mit  Lagentextur  (Banded  veins). 

(a)  Ohue  Symmetrie  der  Lagen  (unsymmetrical). 

(b)  Mit  Symmetrie  der  Lagen  (symmetrical). 
VI.  Gauge  mit  Breccieu  oder  Couglomerattextur. 

(5) 

J.  Le  Conte,  A7ner.  Jour.  Sci.,  July,  1883,  p.  17. 

1.  Fissure  Veins. 

2.  Incipient  Fissures,  or  Irregular  Veins. 

3.  Brecciated  Veins. 

4.  Substitution  Veins. 

5.  Contact  Veins. 

6.  Irregular  Ore  Deposits. 

In  von  Weissenbach's  table  the  sedimentary  veins  are 
much  the  same  as  the  *' sandstones  dikes"  which  J.  S. 
Diller  has  recently  described.  (Bull.  Geol.  Soc.  Amer.,  I., 
411.)  They  and  the  stalactitic  veins  have  small  practical 
value,  although  of  great  scientific  interest.  Under  (d),  the 
stockworks  with  tin  ores  are  the  principal  illustration  of  eco- 
nomic prominence.  The  attrition  veins  are  an  important  class, 
and  increasing  study  has  widened  the  application  of  this  or 

*  Gangziige  is  happily  translated  "linked  veins,"  by  Dr.  G.  F.  Becker 
(Quicksilver  Deposits,  p.  410).  Any  attempt  to  render  the  original  by 
preserving  the  figure  of  a  flock  of  birds  or  of  a  school  of  fish,  etc.,  is,  as 
Mr.  Becker  remarks,  infelicitous,  if  not  impossible. 


APPENDIX  L  451 

synoDymous  terms.  Segregated  veins  and  true  veins  are  well- 
known  forms.  In  the  comments  of  von  Cotta,  which  follow 
von  Weissenbach's  paper,  veins  are  grouped  from  every  possi- 
ble standpoint,  von  Weissenbach's  scheme  being  taken  as  the 
one  based  on  origin.  Nos.  2  and  4  have  small  claims  to  atten- 
tion. No.  3  foreshadows  the  drift  of  many  subsequent  writers. 
The  meanings  of  the  terms  are  self-evident,  except  perhaps 
Gaagzilge  (linked  veins).  This  refers  to  a  group  of  parallel  and 
more  or  less  overlapping  veins,  deposited  along  a  series  of 
opening,  evidently  of  common  origin.  It  is  a  convenient  term. 
The  terms  used  by  Le  Conte  may  be  passed  without  comment 
as  being  self-evident  in  their  meaning,  except  (4)  and  (6).  The 
scheme  was  devised,  as  a  perusal  of  the  citation  will  show, 
after  the  author  had  set  forth  some  original  views  of  the  causes 
which  lead  to  the  precipitation  of  ores,  and  had  forcibly  stated 
others  very  generally  accepted.  In  the  explanatory  text  some 
quite  curious  associations  are  found,  which  are  cited  by  way  of 
illustration.  Thus,  under  group  (4),  stalactites,  caves,  gash 
veins,  and  the  Leadville  ore  bodies  are  considered  examples, 
and  under  group  (6)  the  grouping  together  of  beds,  igneous 
masses,  and  all  other  forms  of  so-called  irregular  deposit  is 
decidedly  open  to  criticism.  This  is  the  more  emphatic  be- 
cause the  concluding  sentences  of  the  paper  (of  whose  general 
value  and  excellence  there  can  be  no  question)  give  the  impres- 
sion that  the  author  felt  he  had  cleared  up  all  the  points  in  the 
origin  of  ore  bodies  which  would  be  of  interest  or  importance 
to  a  purely  scientific  investigator  as  contrasted  with  a  practical 
miner. 

B.   General  Schemes  Based  on  Form, 

(6) 

Von  Cotta  and  Prime.     Ore  Deposits,  New  York,  1870. 
I.  Regular  Deposits. 

A.  Beds. 

B.  Veins. 

(a)  True  (Fissure)  Veins. 
lb)  Bedded  Veins. 

(c)  Contact  Veins. 

(d)  Lenticular  Veins. 


462 


KEMP'S  ORE  DEPOSITS. 


II.  Irregular  Deposits. 

C.  Segregations. 

(a)  Recumbent. 
(6)  Vertical. 

D.  Impregnations  (Disseminations)^ 

(V) 
Lottner-Serlo,  Leitfaden  zur  Berghaukunde,  1869. 
I.  Eingelagerte  Lagerstatten  (Inclosed  Deposits). 

A.  Plattenformige  (Tabular). 

(a)  Gange  (Veins). 

(6)  Flotze  und  Lager  (Strata,  beds,  seams). 

B.  Massige  Lagerstatten  (Massive  Deposits.) 

(a)  Stocke  ) 

(6)   Stockwerke  ) 

C.  Andere  unregelmassige  Lagerstatten  (other  ir- 

regular deposits), 
(a)  Nester  (Pockets). 
(6)  Putzen. 
(c)  Nieren  (Kidneys). 
II.  Aufgelagerte  Lagerstatten  (Superficial  Deposits). 

D.  Triimmerlagerstatten  (Placers). 

E.  Oberflacbliche  Lager  (Surface  beds). 

(8) 
Koehler,  Lehrbuch  der  Bergbaukunde,  1887. 

I.  Plattenformige  Lagerstatten  (Tabular  Deposits). 

(a)  Gange  (Veins). 

(b)  Flotze  und  Lager  (Strata,  beds,  seams). 

II.  Lagerstatten  von  imregelmassige  Form  (Deposits  of 
irregular  Form). 
(a)  Stocke  und  Stockwerke  (Masses). 
(6)  Butzen,  Nester,  und  Nieren  (Pockets,  concre- 
tions, etc.). 

(^) 
Gallon,  Lectures  on  Mining,  1886   (Foster  and  Galloway's 
translation). 
I.  Veins. 
IL  Beds. 
III.  Masses  (i.e.,  not  relatively  long,  broad,  and  thin). 


APPENDIX  I. 


453 


The  scheme  of  von  Cotta  and  Prime  carries  out  the  principle 
of  form  to  its  logical  and  somewhat  trivial  conclusion. 
Thus  under  irregular  deposits  it  is  a  matter  of  extremely  small 
classificatory  moment  whether  an  ore  body  is  recumbent  or 
vertical.  Otherwise  the  scheme  is  excellent,  and  its  influence 
can  be  traced  through  most  of  those  that  are  of  later  date.  The 
original  draft  came  out  in  the  German  in  1859.  All  the  others 
are  from  treatises  on  mining,  in  which  this  subject  plays  a 
minor  role,  and  indicates  the  tendency,  referred  to  above,  of 
mining  engineers,  when  writing  theoretically,  to  imagine  cer- 
tain fairly  definite  forms,  which  are  to  be  exploited.  As  previ- 
ously remarked,  however,  considering  the  uncertainty  of  ore 
bodies  and  their  variability  in  shape,  it  is  here  argued  that  the 
genetic  principle  might  better  take  precedence.  Several  of  the 
German  terms  are  difficult  to  render  into  English  mining 
idioms,  as  for  example,  Stock,  Butzen  (Putzen),  Nester,  and 
Nieren. 

C.  Schemes,  Partly  Based  on  Form,  Partly  on  Origin, 

(10) 

J.  D.  Whitney,  Metallic  Wealth  of  theUnited  States^  1854. 
I.   Superficial. 
11.  Stratified. 

(a)  Constituting  the  mass  of  a  bed  or  stratified  de- 
posit. 
(6)  Disseminated  through  sedimentary  beds, 
(c)  Originally   deposited   from    aqueous  solution, 
but  since  metamorphosed. 
III.  Unstratified. 

A.  Irregular. 

{a)  Masses  of  eruptive  origin. 

{b)  Disseminated  in  eruptive  rocks, 

(c)  Stockwork  deposits. 

{d)  Contact  deposits. 

(e)  Fahlbands. 

B.  Regular. 

(/)  Segregated  veins. 

{g)  Gash  veins. 

{h)  True  or  fissure  veins. 


454  KEMP'S  ORE  DEPOSITS. 

(11) 
J.  S.  Newberry,  School  of  Mines  Quarterly,  March,  1880, 
May,  1880. 
L  Superficial, 
II.  Stratified. 

(a)  Forming  entire  strata. 

(b)  Disseminated  through  strata. 

(c)  Segregated  from  strata. 
III.  Unstratified. 

(a)  Eruptive  masses. 

(6)  Disseminated  through  eruptive  rock. 

(c)  Contact  deposits. 

(d)  Stockworks. 

(e)  Fahlbands. 
(/)  Chambers. 

(g)  Mineral  veins. 

1.  Gash  veins. 

2.  Segregated  veins, 

3.  Bedded  veins. 

4.  Fissure  veins. 

(12) 

J.  A.  Phillips,  Ore  Deposits,  1884. 
I.  Superficial. 

(a)  By  mechanical  action  of  water. 
(6)  By  chemical  action. 
II.  Stratified. 

(a)  Deposits  constituting  the  bulk  of  metalliferous 

beds  formed  by  precipitation  from  aqueous 
solution. 

(b)  Beds  originally  deposited   from   solution   but 

subsequently  altered  by  metamorphism. 

(c)  Ore  disseminated  through  sedimentary  beds,  in 

which  they  have  been  chemically  deposited. 
III.  Unstratified. 

(a)  True  veins. 

(b)  Segregated  veins. 

(c)  Gash  veins. 

(d)  Impregnations. 

(e)  Stockworks. 


APPENDLS I  455 

(/)  Fahlbands. 

{g)  CoDtact  deposits. 

{h)  Chambers  or  pockets. 

It  is  at  once  apparent  that  Whitney's  scheme  contains 
the  essentials  of  the  others,  which  are  merely  slight  modi- 
fications. Newberry  introduces  impregnations,  chambers, 
and  bedded  veins..  The  first  named  is  a  useful  term,  although 
it  is  not  always  easy  to  distinguish  impregnations  from  others 
earlier  given.  Thus,  they  may  be  very  like  the  division,  dis- 
seminated through  strata,  or  disseminated  through  eruptive 
rock,  or,  if  in  metamorphic  rock,  fahlbands.  The  word  is 
also  used  to  indicate  places  along  a  vein  where  the  ore  has 
spread  into  the  walls.  The  term  "chambers,"  or  "caves,"  has 
found  application  in  the  West,  and  is  a  useful  addition. 
Bedded  veins  appear  also  in  von  Cotta  above  (No.  6). 
Phillips  seeks  to  explain  the  methods  of  origin  in  his  use  of 
Whitney's  scheme  and  clearly  feels  the  importance  of  empha- 
sizing the  genetic  principle  more  strongly.  Much  of  it  is  im- 
plied in  the  simpler  phraseology,  however,  and  the  extended 
sentences  lack  the  incisiveness  of  the  earlier  schemes.  The 
arrangement  as  set  forth  hy  Whitney  is  worthy  of  high  praise, 
and  the  scheme  is  one  of  the  manj'  valuable  things  in  a  book 
that  has  played  a  large  part  in  the  economic  history  of  the 
United  States. 

•  D.  Schemes  Largely  Based  on  Origin, 

(13) 

[  J.  Grimm,  Lagerstdtten,  1869. 

I.  Gemengtheile  oder  grossere  Einschlusse  in  den  Ge- 
birgsgesteinen.     Einsprengung,   Impragnation. 
(Essential  component  minerals  and  inclusions  in 
country  rock.     Impregnations.) 
»  (a)  Ursprungliche  Einsprengung.     (Original  with 

the  inclosing  rock.) 
(h)  Von  anderen  Lagerstatten  weggefiihrte  Bruch- 
theile,  etc.     (Fragments  brought  from  a  dis- 
tance.   Placers,  ore- bearing  boulders.    Brec- 
cias. ) 


456  KEMP'S  ORE  DEPOSITS. 

11.  Untergeordnete  Gebirgsglieder  oder  besondere  Lager-> 
statten.      (Subordinate  terranes  or  special  forms 
of  Deposits.) 
(a)     PlatteDformige  Massen.     (Tabular  masses.) 

1.  Lager  oder  Flotze.     Bodensatzbildung. 

(Beds,  strata.) 

2.  Gange,      Kliifte,     Gangtrummer,     etc. 

(Veins  of  varying  sizes.) 

3.  Plattenformige  Erz-ausscheidungen  und 

Anhaufungen.      (Segregated  veins.) 
if))  Stocke  und  regellos  gestaltete  Massen.     (Stocks 
and  irregular  masses. ) 

1.  Lagerstocke  Linsenstocke,Linsen.   (Len- 

ticular deposits,  etc.) 

2.  Stocke,  Butzen,  Nester,  etc.      (Masses, 

pockets,  etc.) 

3.  Stockwerke.     (Stockworks. ) 

(14) 

A.  von  Groddeck,  Lehre  von  den  Lagerstdtten  der  Erze.y 

1879,  p.  84. 
I.  Urspriinglicbe  Lagerstatten  (Primary  deposits). 

A.  Gleicbzeitig  mit  dem  Nebengestein    gebildet. 

(Formed  at  tbe  same  time  v^ith  the  walls. ) 

1.  Geschichtete.     (Stratified.) 

(a)  Derbe  Erzflotze.   (Entire  beds  in  a  stratified 

series. ) 
(6)  Ausscheidungsflotze.       (Disseminated      in 

beds. ) 
(c)  Erzlager.     (Lenticular     beds,    mostly     in 

schists.) 

2.  Massige.     (Massive;  the  vrord   is  nearly 

synonymous  vs'ith  igneous.) 

B.  Spater  wie  das  Nebengestein  gebildet.   (Formed 

later  than  the  walls.) 
3.   Hohlraumsfullungen.     (Cavity  fillings.) 
(a)  Spaltenfiillungen  oder  Gange.    (Fissure  fill- 
ings or  veins.) 
(1)  In   massigen   Gesteinen.      (In    igneous 
rocks.) 


APPENDIX  I. 


457 


(2)  In  geschicbteten  GesteiDen.     (In  strati- 
fied rocks). 
(&)  Hohlenfiillungen.     (Chambers.) 

4.  Metamorpbiscbe  Lagerstatten.    (Altera- 
tions, replacements,  etc. ) 
II.  Triimmer-lagerstatten.     (Secondary    or    detrital   de- 
posits. ) 

(15) 
R  Pumpelly,  Johnson's  Encyclopcedia,  1886,  VI.,  22 
I.  Disseminated  concentra- 
tion. 
(a)  Impregnations,  Fabl- 
bands. 
II.  Aggregated  Concentration. 

(a)  Lenticular    aggrega- 

tions and  beds. 

(b)  Irregular  masses. 

(c)  Reticulated  veins. 

(d)  Contact  deposits. 

III.  Cave  deposits. 

IV.  Gash  veins. 
V.  Fissure  veins. 

VI.  Surface  deposits. 

(a)  Residuary  deposits. 

(b)  Stream  deposits. 

(c)  Lake  or  bog  deposits. 

These  three  are  all  excellent,  and  give  some  interesting 
variations  in  the  several  points  of  view  from  which  each 
writer  regarded  his  subject.  There  are  instances  in  the  two 
German  schemes  where  it  is  difficult  to  render  the  original  into 
a  corresponding  English  term  and  recourse  has  been  had  to 
the  explanatory  text.  Grimm  especially  writes  an  obscure 
style.  He  divides  accordingly  as  the  ore  forms  an  essential 
and  integral  part  of  the  walls  or  a  distinct  body.  Von  Grod- 
deck  has  in  view  the  relative  time  of  formation  as  contrasted 
with  the  walls.  Grimm  afterward  emphasizes  geometrical 
shape,  but  this  von  Groddeck  practically  does  away  with,  and 
continues  more  consistently  genetic.  His  scheme  might  per- 
haps come  more  appropriately  in  the  next  section. 


Forms  due  to  the  text- 
ure of  the  inclosing 
rock,  or  to  its  mineral 
constitution,  or  to 
both  causes. 


Forms  chiefly  due  to 
pre-existing  open  cav- 
ities or  fissures. 


458 


KEMP'S  ORE  DEPOSITS. 


Pumpelly's  conception  varies  considerably  from  the  others. 
He  writes,  as  his  full  paper  states,  in  the  belief  that  the  metals 
have  all  been  derived  primarily  from  the  ocean,  whence  they 
have  passed  into  sedimentary,  and,  by  fusion  of  sediments, 
into  igneous  rocks.  The  group  of  residuary  surface  deposits, 
carrying  out  as  it  does  a  favorite  idea  of  Professor  Pumpelly, 
as  set  forth  in  his  papers  on  the  secular  decay  of  rocks,  is  an 
important  distinction. 

E.  Schemes  Entirely  Based  on  Origin. 


(16) 

H.  S.  Munroe.     Used  in  the   Lectures  on  Mining  in  the 
School  of  Mines,  Columbia  University. 
I.  Of  surface  origin,  beds. 

{a)  Mechanical  (action  of  moving  water). 

1.  Placers  and  beach  deposits. 
(6)  Chemical  (deposited  in  still  water). 

1.  By  evaporation  (salt,  gypsum,  etc.). 

2.  By  precipitation  (bog  ores). 

3.  Residual  deposits  from  solution  of  lime- 

stone, etc.  (hematites), 
(c)  Organic. 

1.  Vegetable  (coal,  etc.). 

2.  Animal  (limestone,  etc.). 

{d)  Complex  (cannel  coal,  bog  ores,  etc.). 
IL  Of  subterranean  origin. 

(a)  Filling  fissures  and  cavities  formed  mechani- 
cally. 

1.  Fissure  veins,  lodes. 

2.  Cave  deposits — lead,  silver,  iron  ores. 

3.  Gash  veins.     The  cavities  of  2  and  3  are 

enlarged  by  solution  of  limestone. 
(6)  Filling   interstitial   spaces  and   replacing  the 
walls. 

1.  Impregnated  beds. 

2.  Fahlbands. 

3.  Stockworks. 

4.  Bonanzas. 
5. 


APPENDIX  L  459 

This  scheme  covers  all  forms  of  mineral  deposits,  whether 
metalliferous  or  not,  while  most  of  those  previously 
given,  as  well  as  the  one  that  follows,  concern  only  metallifer- 
ous bodies.  The  scheme  is  consistently  genetic  and  was  elab- 
orated because  such  an  one  filled  its  place  in  lectures  on  min- 
ing better  than  one  based  on  form.  The  general  principle  on 
which  the  main  sub-division  is  made  differs  materially  from 
any  hitherto  given.  Deposits  formed  on  the  surface  are  kept 
distinct  from  those  originating  below,  even  though  the  first 
class  may  afterward  be  buried.  It  is  immediately  after  this 
scheme  that  the  one  in  paragraph  1.06.05  finds  its  place. 

In  the  report  of  the  State  Geologist  of  Michigan  for  1891-92 
(issued  January,  1893),  pp.  144,  145,  Dr.  M.  E.  Wadsworth 
has  published  a  '* Preliminary  Classification  of  Metalliferous 
or  Ore  Deposits."    The  main  outline  is  as  follows : 

I.  Eruptive  Deposits      {a)  Non-Fragmental. 

{h)  Fragmental. 
II.  Mechanical  Deposits  {a)  Unconsolidated. 

(6)  Consolidated. 
III.  Chemical  Deposits     (a)  Sublimations. 

(6)  Water  Deposits. 

(c)  Impregnations  or  ^Replace- 

ments. 
{d)  Segregations  or  Cavity  De- 
posits. 

Each  of  the  above,  except  III.  (d),  is  then  subdivided  so  that 
the  table  becomes  practically  a  classification  of  rocks.  Indeed, 
a  moment's  consideraton  will  show  that  the  scheme  in  its 
main  divisions  is  closely  modeled  after  the  prevailing  classifi- 
cation of  rocks.  III.  (d)  Segregations  or  Cavity  Deposits  con- 
tains the  following:  1.  Pockets.  2.  Chambers.  3.  Contact 
Deposits.  4.  Veins,  including  Gash  Veins,  Segregated  Veins, 
Reticulated  Veins  or  Stockworks,  Contact  Veins,  Fissure  or 
Fault  Veins. 

The  author  states  in  some  appended  comments  that  the  table 
is  not  limited  to  those  deposits  now  practically  worked  (which 
we  ordinarily  understand  the  expression  ore  deposits  to  mean), 
but  is  intended  to  include  all  that  have  been  or  may  be  of  value. 
But  in  this  respect  there  is  good  ground  for  preferring  to  make 


460 


KEMP'S  ORE  UEF0SIT8. 


our  classifications  in  ore  deposits,  as  in  mineralogy,  zoology, 
etc.,  embrace  only  the  authenticated  varieties,  expecting  addi- 
tions to  be  incorporated  as  discovered  and  suitably  described. 

The  same  general  grouping  as  this  scheme  employs  is  inde- 
pendently adopted  by  R.  S.  Tarr,  in  the  Economic  Geology  of 
the  Lnited  States,  1894. 

For  the  meeting  of  the  American  Institute  of  Mining 
Engineers,  held  in  connection  with  the  various  congresses 
at  the  World's  Fair  in  Chicago,  July,  1893,  Professor  Franz 
Posepny,  of  Vienna,  contributed  a  grand  essay  on  the  "Origin 
of  Ore  Deposits."  The  materials  for  it  were  specially  as- 
sembled by  Professor  Posepny  while  giving  a  course  of  lectures 
at  the  Pribram  Mining  Academy  in  the  ten  years  following 
1879.  The  paper  is  a  theoretical  discussion  of  the  origin  of 
ores,  with  illustrations  selected  from  all  parts  of  the  world, 
but  especially  from  Europe  and  America.  It  forms  one  of 
the  most  important  contributions  to  the  literature  that  has  yet 
been  made.  Posepny  distinguishes  at  the  outset  between  rocks 
and  mineral  deposits;  i.e.,  between  original  materials,  such 
as  wall  rock,  and  secondary-  introductions,  such  as  veins,  etc. 
The  former  he  calls ''idiogenites,"  the  latter '^xenogenites," 
basing  the  names  on  the  familar  Greek  terms  that  run  through 
all  our  literature.  The  latter  are  especially  characterized  by 
"crustification,"  by  which  term  is  indicated  what  has  been 
called  "banded  structure,"  on  p.  47.  The  subject  of  cavities 
is  then  taken  up,  and,  while  minute  pores  are  stated  to  be  in 
all  rocks,  a  distinction  is  made  between  the  larger  openings, 
which  originate  in  a  rock  mass  as  a  part  of  its  own  structure, 
such  as  contraction  joints  in  igneous  rocks,  amygdaloids,  and 
the  like,  and  those  induced  by  outside  causes,  such  as  fault 
fissures. 

The  circulation  of  water  through  these  is  next  treated  :  first, 
surface  waters  or  "vadose"  circulations,  which  descend; 
second,  ascending  waters  from  great  depths,  such  as  springs 
in  deep  mines,  hot  springs,  etc.  The  common  salts  in  solution 
in  these  latter  are  tabulated,  being  of  course  mostly  alkaline 
carbonates,  sulphates,  chlorides,  etc.  The  "exotic"  metallic 
admixtures  which  would  bear  on  the  origin  of  ores  are  next 
discussed,  so  far  as  possible  with  analyses  of  actual  cases.  The 
alterations  produced  by  mineral  springs  in  rocks  and  the  struc- 


APPENDIX  I.  401 

"tural  relations  of  the  deposits  of  mioeral  springs,  especially  as 
expressed  by  "crustifieation,"  are  then  described.  This  pre- 
liminary material  clears  the  way  for  the  general  discussion 
of  the  origin  of  ore  bodies.  The  argument  running  all  through 
the  paper  is  that  ore  bodies,  even  when  apparently  inter  bedded 
with  sedimentary  rocks,  are  of  secondary  introduction  and,  in 
general  for  veins,  are  from  deep-seated  sources.  Precipitation 
from  descending  solutions  and  filling  by  lateral  secretion  are 
strongly  controverted. 

The  discussion  of  origin  follows  in  its  arrangement  the  fol- 
lowing classification  of  ore  deposits: 

I.     Filling  of  spaces  of  discission  (fissures). 
II.     Filling  of  spaces  of  dissolution  in  soluble  rocks. 

III.  Metamorphic  deposits  in  soluble  rocks;  in  simple  sedi- 
ments; in  crystalline  and  eruptive  rocks. 

IV.  Hysteromorphic  (i.e.,  later  or  last  formed)  deposits. 
Secondary  deposits  due  to  surface  action  (i.e.,  placers,  etc.). 

The  treatment,  both  in  the  introductory  pages  and  in  the 
later  discussions,  is  often  strikingly  similar  to  that  of  this  book, 
and  the  underlying  argument  is  much  the  same.  The  stand- 
point in  both  essays  is  essentially  a  genetic  one,  and  the  main 
difference  lies  in  the  fact  that  the  one  is  an  exposition  of  an  in- 
dividual's views,  fortified  by  examples  from  all  parts  of  the 
world ;  the  other  endeavors  to  be  a  judicial  statement,  with  a 
fairly  complete  description  of  the  ore  bodies  of  the  United 
States  and  Canada  alone.  The  writer  differs  with  Posepny 
however  in  the  greater  weight  given  to  the  ores  of  igneous 
origin. 

1.06.28.  An  extended  treatise  on  the  useful  minerals,  earthy 
as  well  as  metallic,  by  MM.  E.  Fuchs  and  L.  De  Launay,  has 
recently  appeared  {Traite  des  Gttes  Mineraux  et  Metalli- 
feres,  Paris,  1893).  The  book  is  based  on  the  lectures  on 
economic  geology  delivered  in  the  Ecole  Superieure  des  Mines, 
at  Paris,  in  the  last  fifteen  years  by  the  two  authors.  (Pro- 
fessor Fuchs  died  in  1889,  and  was  succeeded  by  Professor  De 
Launay.)  A  vast  amount  of  valuable  information  is  brought 
together  and  discussed  from  various  points  of  view,  useful 
applications  and  methods  of  treatment  being  set  forth  as  well 
as  geological  occurrence.     The  work  ife  encyclopedic  in  scope 


462 


KEMP'S  ORE  DEPOSITS. 


and  affords  a  reader  descriptioDSof  mineral  resources  and  refer- 
ences to  their  literature  in  every  quarter  of  the  world.  So  far, 
however,  as  the  United  States  are  concerned  the  authors  have 
suffered  from  the  unavoidable  limitations  of  those  not  native 
and  conversant  in  a  discriminating  way  with  our  literature. 
Nevertheless  they  have  endeavored  to  give  a  large  share  of 
their  space  to  this  country,  and  where  prominent  monographs 
have  appeared  they  have  been  read  with  care,  but  in  many 
cases  reference  to  later  papers  and  descriptions  would  have  im- 
proved the  text.     A  later  edition  will  doubtless  correct  these. 

The  classification  of  ore  deposits  as  well  as  other 
useful  minerals  on  a  genetic  principle  has  evidently  been  in 
many  minds  in  the  last  few  years.  Mr.  Frederick  Danvers 
Power, ^  of  Melbourne,  Victoria,  reviewed  the  subject  in  1892, 
and  after  giving  the  schemes  of  others  and  summing  up  the 
various  characteristics  of  veins,  has  formulated  a  classification 
whose  main  divisions  are  as  follows:  I.  Contemporaneous; 
Indigenous.  II.  Metasomatic  or  Chemical  Alteration  of  the 
Original  Constituents.  III.  Subsequently  Introduced ;  Exotic. 
Each  of  these  has  then  a  number  of  subdivisions  too  numerous 
to  be  repeated  here. 

Prof.  William  O.  Crosby,^  of  Boston,  has  recently  discussed 
the  same  subject  in  a  very  suggestive  way.  The  main  head- 
ings are:  A.  Deposits  of  Igneous  Origin  (Igneous  rocks) ;  B. 
Deposits  of  Aqueo-Igneous  Origin;  C.  Deposits  of  Aqueous 
Origin.  The  first  and  last  are  then  subdivided  at  considera- 
ble length,  but  the  second  is  chiefly  limited  to  the  pegmatite 
(granitic)  veins  which  attend  many  plutonic  intrusions.  Lack 
of  space  prevents  the  full  reproduction  of  both  these  schemes, 
but  sufficient  has  been  mentioned,  it  is  hoped,  to  indicate  the 
line  of  attack  and  to  place  a  reader  desiring  to  look  the  sub- 
ject up  in  touch  with  the  originals. 

*  "  The  Classification  of  Valuable  Mineral  Deposits,"  Trans.  Australas. 
Inst.  Min.  Eng.,  1893. 

^  "A  Classification  of  Economic  Geological  Deposits  based  on  Origin 
and  Original  Structure,"  Amer.  Geol.,  April,  1894,  p.  240.  The  paper  also 
appears  in  the  Technological  Qimrterly, 


INDEX. 


Abiquiu,  N.  M.,  copper  ores,  224. 
Acadian  stage,  4, 
Adairsville,  Ga.,  aluminum,  404. 
Adams,  F.  D.,  on  ores  of  Treadwell 

Mine,  391. 
Adams  Co.,  Penn,,  limonites,  104. 
Adams  Co.,  Ohio,   Clinton  ores,  114, 

115. 
Adirondacks,  N.  Y.,  magnetites,  160. 
Admiralty  Islands,  Alaska,  gold  de- 
posits, 392. 
Agglomerates,  281. 
Ainsworth  District,  B.  C. ,  gold  mines, 

394,  395. 
Alabama,  aluminum,  (bauxite),  404. 

Clinton  ore,  114,  117. 

Copper,  194. 

Gold  mines,  378. 

Limonites,  104. 

Tin  ores,  444. 
Alaska,  geology  of,  885. 

Gold,  392. 

Treadwell  mines,  390. 
Alder  Gulch,    Madison    Co.,   Mont., 

317. 
Aleutian  Islands,  Alaska,  385. 
Algonkian  system,  4. 
Allamakee  Co.,  Iowa,  limonite,  98,  99. 
Almaden,  Spain,  mercury,  424. 
Alno,  Sweden,  61,  175. 
Alta  mine,  Jefferson  Co.,  Mont.,  317. 
Alturas  Co.,  Idaho,  327. 
Aluminum,  in  bauxite,  404. 

Origin,  404-410. 

Sources,  403. 
Amador  Co.,  Cal.,  copper  mines,  195. 
Animikie  series,  4. 
Annie  Lee  mine,  Colo. ,  298,  305. 
Anthony's  Nose,  N.  Y.,  nickel  ores, 
430. 

Pyrite  ores,  184. 
Anticlines,  arrested,  11. 

Defined,  11. 

With  shattered  bends,  17,  19. 
Antigonish  Co.,  Nova  Scotia,  hema- 
tite, 120. 


Antimony,  410. 

Apache  Co.,   Ariz.,  silver  and  gold 

ores,  335. 
Apollo  mine,  Unga  Island,  Alaska, 

392. 
Appalachians,  general  description,  7. 
Geology  of  gold  deposits,  376. 
Manganese  ores,  418. 
Appendix,  447. 

Remarks  on,  448. 
Appleton,  Wis.,  fold  at,  20. 
Archean  Group,  classification,  4. 
Argentine,    Clear  Creek  Co. .    Colo , 

295. 
Arizona,  copper  mines,  214-220. 
Geology,  334. 
Gold  deposits,  334. 
Lead -silver  ores,  279. 
Silver  deposits,  334. 
Arkansas,  antimony,  411. 
Bauxite,  404-406. 
Iron  ores,  96,  97. 
Manganese,  420. 
Nickel,  440. 
Silver  mines,  283. 
Arksut  Fjord,  Greenland,  403. 
Arlington,  N.  J.,  copper  mines,  223. 
Armstead  H.   H.,   Jr.,  gold  ores,  of 

Idaho,  324. 
Arrow  Lakes,  B.  C,  upper  and  lower, 

394. 
Arsenic  deposits,  412. 

(See  Gold  in  Canada.) 
Ascension  by  infiltration,  40,  41-43. 
Ashcroft  iron  mines,  Colo.,  170. 
Ashland  mine.  Iron  wood,  Mich.,  142. 
Aspen,  Pitkin  Co.,  Colo.,  45. 
Iron  mines,  170, 
Lead  and  silver,  268. 
Atlanta,  Elmore  Co.,  Idaho,  325. 
Atlantic  Border  gold,  283. 
Lead,  226. 
Silver,  283. 
Augusta  Co.,  Va.,  manganese,  418. 
Auriferous  beach  sands.  348. 
Gravels,  353. 


h 


464 


INDEX. 


Austin,  Nev.,  antimony,  411. 
Gold  and  silver  ores,  339. 
Avala,  Servia,  mercury,  434. 

B. 

Bachelor  Mt.,  Colo.,  293. 
Baker  Co.,  Ore.,  347. 

Gold  mines,  348. 
Bald  Butte  Group,  Deer  Lodge  Co., 

Mont.,  320. 
Baldy  Mt.,  Utah,  333. 
Baltimore  Region,  chromite,  414. 
Banded  structure  of  veins,  47. 
Bannack  City,  Mont. ,  317. 
Banner  district,  Idaho,  325. 
Barker  mining  district,  Meagher  Co. , 

Mont.,  320,  321. 
Barton  Hill,  N.  Y.,  magnetite,  162. 
Barus,  C,    on  electrical  activity  in 
veins,  52,  53. 

Experiments  on    the    Comstock 
Lode,  343. 
Basal  granite,  388. 
Bassick  mine,  Colo.,  47,  49,  58,  296. 
Batesville,  Ark.,  manganese,  420. 
Bath  Co.,  Ky.,  Clinton  ores,  115. 
Battle  Mt.,  Teller  Co.,  Colo.,  305. 
Bauxite,  404-407. 
Bayley,  W.  S. ,  on  Michigan  iron  ores, 

127    129 
Bear  Lake  Co.,  Idaho,  327. 
Bearpaw  Mt.,  Mont.,  323. 
Beaver  Co. ,  Utah,  gold  and  silver,  333. 
Beayerhead  Co. ,  Mont. ,  gold  and  sil- 
ver, 317. 
Becker,  G.  F.,  on  Alaska  mines,  390. 

On  cinnabar,  30,  44,  373. 

On  Comstock  Lode,  origin,  340- 
344. 

On  gold  ores,  35,  376,  378. 

On  gold  in  Mad  Ox  mine,  Cal., 
368. 

On  gravel  beds,  Cal.,  356. 

On  joints,  15. 

On  quicksilver,  425. 

On  silver  ores,  35. 

On  Soret's  principle,  67. 

On  Sulphur  Bank  mine,  427.  . 

On  Washoe  rocks,  345. 
Beds  defined,  6. 
Bell,  Robert,   on  Hudson  Bay  gold 

ores,  338. 
Belmont,  Nev.,  srold  and  silver  ores, 

338. 
Belt  formation  of  Montana,  315. 
Bench  gravels,  Alaska.,  393. 
Bennet  mines,  Alaska,  392. 
Benson  mine,  N.  Y.,  iron  ores,  166. 
Benton  stage,  5. 
Bei'ks  Co.,  Penn.,  iron  ores,  169. 


Bernallilo  Co.,  N.  M.,  286. 
Berner's  Bay,  Alaska,  gold,  392. 
Bertha  mines,  Va.,  zinc,  247. 
Bessemer    limit    of     Lake    Superior 

ores,  85. 
Beulah  antimony  mine,  Nev.,  411. 
Big  Cottonwood  Canon,  Utah,  274. 
Big  Creek,  Nev.,  411. 
Big  Hill,  Penn.,  175. 
Bingham  Caiion,  Utah,  329. 
Bingham  Co.,  Utah,  274. 
Birch  Creek  series,  388. 
Birmingham  district,  Ala.,  iron  ores, 

118. 
Bisbee,  Ariz.,  copper,  217. 

Region^  gold  and  silver,  336. 
Bischoff ,  on  silicate  of  gold,  372. 
Bismuth,  412. 

Bitter  Root  Mts.,  Idaho,  323. 
Black-band  iron  ore,  107. 
Black  Hills,  S.  D.,  57. 

Geology,  309. 

Gold  in  Potsdam,  309. 

Placers,  309. 

Tin,  442. 
Black  Hornet  district,  Idaho,  325. 
Black  Lake  asbestos  mine,  416. 
Black  range  copper  mines,  Ariz. ,  220. 
Blake,    W.    P.,   aluminum    deposits, 
N.  M.,  407. 

Antimony  ores,  Utah,  411. 

Copper  Basin  ores,  Ariz.,  221. 

Deep  Creek  ores,  Utah,  332. 

Gold  and  silver.  Tombstone.  336. 

Lead  and  zinc  ores,  236. 

Mercury,  Texas,  428. 

Silver  King  mine,  Ariz.,  336. 

Zinc  ores,  N.  M.,  259. 
Blanco  stage,  5. 
Blende  in  the  Rocky  Mts.,  258. 
Blezard  mine,  Ontario,  436. 
Block  iron  ore,  107. 
Block  Island,  R.  I.,  magnetite  sands, 

181. 
Blow,  A.  A.,  cited  on  faults.  21,  22. 

Origin  Leadville  ores,  265. 
Blue  lead  in  Cal. ,  gravels,  355. 
Blue  Mts.,  Oregon,  347. 
Bodie,  Cal. ,  gold  and  silver,  353. 
Bog  iron  ore,  87-93. 
Boise  district,  Idaho,  325. 
Bonanza  City,  Idaho,  325. 
Bonanza,  defined,  49. 
Bonne  Terre,  Mo. ,  lead  mines,  228. 
Bonneville,  Lake,  Nev.,  337. 
Bonsacks,  Va. ,  illustration  of  gossan, 
51. 

Zinc  mines,  249. 
Boss  of  igneous  rock  defined,  12. 
Boston  Mt.,  Ark.,  421. 


INDEX. 


465 


Boulder  Co.,  Colo.,  306. 
Iron  ores.  109.  170. 
Box  Elder  Co..  Utah,  329. 
Boyd.   C.  R.,  Bertha  mine  zinc  ores, 

248. 
On  production  of  Big  Hill  mine, 

Penn.,  179. 
Boye,  Dr.,  iron  ores,  102. 
Boyertown,  Penn.,  iron  mines,  179. 
Bradley,  F.  P. .  on  limonites,  104. 
Brandon,  Vt.,  iron  ores,  100. 

Manganese  ores,  418. 
Branner.  J.  C.  origin  of,  Ark.,  alu- 
minum, 406. 
Brazil,  iron  ores,  175. 
Brewer  mine,  S.  C.  380. 
Bridal  chamber  mine,  N.  M.,  361. 
Bridger  stage,  5. 

Bristol,  Conn.,  copper  deposits,  223. 
British  Columbia  gold  gravels,  324. 

Platinum,  441. 
Britton,  N.  L.,  on  Staten  Island  bog 

ores,  91. 
Magnetite  ores,  N.  Y. ,  167. 
Broadwater  Co.,  Mont.,  319. 
Brooks,  T.  B.,  on  Marquette  district, 

135. 
Browne,  D.  H.,  on  isochemic  lines, 

183. 
Browne,  R.  E. ,  on  California  gravels- 

361. 
Bryant,  Ark.,  aluminum,  406. 
Bucks  Co.,  Penn.,  iron  ore,  169. 
Buckwheat  zinc  mine,  N.  J.,  253. 
Buena  Vista    mine.    Cripple    Creek, 

Colo.,  305. 
Bull  Domingo  mine,  Colo.,  49,  297. 
BullMt.,  Colo.,  305. 
Burden  spathic  ore  mines,  Hudson. 

N.  Y.,  110. 
Burra  Burra  mine,  Tenn. ,  192. 
Pm-ro  Mt..  New  Mexico,  285. 
Putte,  Mont.,  36,  44,  51,  58,  315. 
Copper  ores,  196,  199,  200,  202. 
Development  of,  200. 
Placers  near,  354. 


Jalaveras  Co. ,  Cal.,  195. 

Caldwell  Co.,    Ky.,    lead    and    zinc 

mines,  239. 
Caledonia,  iron  mines,  Mo.,  125. 
Calico,  silver  district,  Cal.,  351. 
California  Bar,  Idaho,  324. 
California,  antimonv,  410;  chromite, 
415. 

Copper  mines,  195. 

Geology,  349. 

Gold  gravels,  353,  360,  361. 

Gulch,  near  Leadville,  Colo.,  295. 


California,  Lead-silver  ores,  279. 

Magnetite,  171. 

Mercury,  424. 

Platinum,  441. 

Tin,  325.  ^ 

Gallon,  on  scheme  of  classification  of 

ore  deposits,  452. 
Calloway  Co.,  Tenn.,  192. 
Calumet   and    Hecla  copper  mines, 

Mich.,  208. 
Calvin,  S. ,  on  limonites,  99. 
Cambrian  system,  4. 
Campbell  Mt.,  Colo.,  293. 
Campbell,  J.  L. ,  on  limonites,  94. 
Camp  Floyd  district,  Utah,  330. 
Campo  Seco,  Cal. ,  copper  mine,  196. 
Canada,  gold,  400,  412. 

Magnetite  ore  mines,  166,  172. 
Canadian  Northwest,  geology,  385. 

Series,  4. 
Caiion  City,  Colo. ,  zinc  works,  258. 

Diablo,  Ariz.,  19. 
Cape  Ann  granite,  13,  14. 
Cape  Breton,  Nova  Scotia,  gold  ores, 
397. 

Manganese  ores,  422. 
Capelton,  Quebec,  pyrite  mine,  184. 
Carbonate  iron  ores,  107. 

Lead-silver,  S.  D.,  272. 

Lead-silver,  Utah,  276. 
Carboniferous  series,  5. 

System,  5. 
Carbonic  acid  in  subterranean  waters. 

28. 
Caribou  Hill,  Colo.,  magnetite,  174. 
Carlyle,  W.  A  ,  on  Slocan  veins,  895. 
Carolinian  gold  belt,  378. 
Carpenter,  F.  R.,  on  Black  Hills  tin, 

443. 
Carroll  Co.,  Md.,  iron  ore,  102. 

Va.,  iron  ore,  103. 
Cartersville,  Ga.,  manganese,  418. 
Cascade  Co.,  Mont.,  321. 

Mts.,  Cal,  349. 
Cascaria,   Durango,   Mex.,   tin  ores, 

444. 
Cason  property,  Ark.,  421. 
Cassia  Co.,  Idaho,  327. 
Cassiar  district.  Alaska,  393. 
Cassiterite,  441. 

Castillo  Co.,  Colo.,  magnetite,  170. 
Castle  Mts.  district,  Mont.,  320. 
Cave  mine,  Utah,  lead  silver  ore,  58, 

276. 
Cave  Spring  manganese  mines,  Ga., 

420. 
Cavities,     secondary    modifications, 

26. 
Cayuga  Co.,  N.  Y.,  Clinton  iron  ores, 
115. 


486 


INDEX. 


Cazin,  F.  M.  F.,  on  Silver  Reef,  Utah, 

ores,  333. 
Cebolla    district,    Colo,,     magnetite, 

175. 
Cedar  Mt.,  Mo.,  157. 
Ceilozoic  Group,  5. 
Central  California,  349. 
Central  district,  Mich. ,  copper,  208. 
Cerro  de  Mercado,  Mex.,  iron  ores, 

187. 
Cerro  Gordo  district,  Cal.,  353. 
Chaffee  Co.,  Colo.,  395. 

Magnetite,  170. 
Chalcopyrite,  of  igneous  origin,  61- 
65. 

With  pyrite,  189. 
Chamber  deposits,  58. 
Chamberlin,  T.  C,  68. 

On  Lead  ores,  335,  236. 
Champlain  series,  5. 
Chandler  and  Pioneer  mines,  Minn., 

148. 
Chapin  mine,  Mich. ,  138. 
Charlemont,  Mass. ,  pyrite  mines,  184, 
Charles  Dickens  mine,  335. 
Chateaugay  iron  mines.  N.  Y. ,  85. 
Chatham,  Conn.,  nickel  ore,  430. 
Chattahoochee  stage,  5. 
Chattanooga,  Tenn.,  iron  ores,  117. 
Chaudiere  River,  Can.,  gold  gravels, 

400. 
Chauvenet,  R.,  on  Colorado  magne- 
tite, 170. 

Iron  ores,  98. 
Chazy  stage,  4. 
Cheever  mine,  N.  Y.,  163. 
Chemung  series,  5. 
Cherokee  Co. ,  Kansas,  340. 
Cherry  Creek,  Mo.,  315. 
Cherry  Valley,  Mo.,  133. 
Chester,  A.  H.,  on  yield  of  standard 
iron  ores,  85. 

Co.,  Penn.,  aluminum  ores,  407. 

F.  D.,  on  chromite,  415. 

Mass.,  alumium  deposits,  410. 
Chibas,  E.  J.  gold  mining,  Columbia, 

399. 
Chico  stage,  5. 
Chipola  stage,  5. 
Chisholm,  F.  F.,  on  Cuban  iron  ore, 

187. 
Choteau  Co.,  Mont.,  333. 
Chromite,  analysis,  414. 

Dissemination  in  serpentine,  414. 

Of  igneous  origin,  61,  63. 

Uses,  414. 
Chromium,  413. 
Chugwater  Creek,  Wyo.,  iron  ores, 

171. 
Churchill  Co. ,  Nev. ,  silver  ores,  340. 


Church,  J.   A.,  on  Comstock  Lode, 
340. 

On  faults,  34. 
Chutes,  49. 
Cincinnati  stage,  4. 

Uplift,  9. 
Cinnabar,  434. 
Claiborne  stage,  5. 
Clarke  Co.,  Mont.,  330. 
Clarke,  E.,  on  lead-silver  ores,  Lake 

Valley,  N.  M.,  361 
Clarke,  F.  W.,  on  earth's  crust,  447. 
Clarke  Timber  Reserve,  Mont. ,  331. 
Classification  of  ore  deposits,  447. 
Clay,  attrition,  in  a  vein,  49. 

Ironstone,  106. 

Seam,  selvage,  49. 
Clayton,  J.  E.,  cited,  49,  319. 
Clear  Creek  Co.,  Colo.,  306. 
Clear  Lake,  Cal.,  437. 
Clerc,  F.  L.,  on  Missouri  ores,  340, 

343. 
Cliff  copper  mine,  Mich. .  308. 
Clifton  copper  district,  Ariz,,  336. 
Clinton  Co.,  Ohio,  114. 

Ores.  57.  114,  131,  446. 

Stage,  4. 
Coal  measures,   classification   of,  in 

Penn.,  107. 
Coastal  Plain,  7,  376. 
Coast  Range,  Cal.,  349,  445. 

Mercury,  434. 
Cobalt,  in  Sudbury  Region,  438. 

(/Sfee  nickel,  416.) 
Cochise  Co.,  Ariz.,  lead-silver,  379. 
Coeur  d' Alene,  Idaho,  lead-silver  ores, 

374,  334. 
Colfax  Co.,  N.  M.,  silver  and  gold, 

386. 
Colombia,  South  America,  441. 
Colorado,  Creede,  gold  ores,  393. 

Geology,  386. 

Iron  ores,  98,  170,  174. 

Lead-silver  mines,  363-372. 

Magnetite,  170. 

Plateau,  445. 

Stage,  5, 

Silver  and  gold,  386-307. 
Columbia  Co.,  N.  Y.,  lead  ores,  227 

Limonites,  101. 
Columbia  Hill,  Cal.,  gold  gravels,  354. 

Mines,  Idaho,  324. 

River  district,  B.  C,  394. 
Comanche  stage,  5. 
Commonwealth  mines,  Mich. ,  138. 
Comstock  Lode,  20,  35. 

Geology  of,  340-345. 
Comstock,  T.  B.,  on  Colorado  gold 
ores,  388. 

On  Colorado  lead-silver  ores,  732. 


INDEX 


467 


Conejos  Co. ,  Colo. ,  296. 
Connecticut  bismuth,  413. 

Copper  contact  deposits,  323. 

Lead  mines,  237, 

Limonite,  101. 

Nickel  ores,  430. 
Contact  deposits,  58,  69. 
Continental  divide,  331. 

Montana,  315. 
Coosa  Valley,  Ga. ,  aluminum,  404. 
Copper  Basin,  Ariz. ,  330. 
Copper  Cliff  mine,  Ont.,  436. 
Copper  Creek,  Colo.,  394. 
Copper  districts  in  Arizona,  331. 
Copper  Falls  district,  Mich. ,  308. 
Copper  Mt.,  Ariz.,  315. 
Copperopolis,  Cal.,  196. 
Copperopolis  mine,  Utah,  331. 
Copper  ores,  analysis,  189. 

Discovery  of,  in  Michigan,  211. 

In  mine  waters,  52. 

In  sandstone,  223,  333. 

Origin  of,  309. 
Copper,  tables  of  production,  83,  90, 

97,  335. 
Corniferous  stage,  5. 
Cornwall,  Penn.,  iron  mines,  85,  175. 
Cortland  series,  61. 
Corundum  of  igneous  origin,  56,  61,  63. 
Cotta,  B.  von,  cited,  451. 

On  method  of  vein  filling,  39. 

On  schemes  of  classification    of 
deposits,  449. 
Courtis,  W.  M.,  on  gold  quartz  363. 
Cow  Bay,  Nova  Scotia,  399. 
Cramer,  F. ,  on  faults,  20. 
Cranberry,  N.  C,  magnetite,  169. 
Crawford  Co.,   Mo.,   hematites,     69, 

133. 
Credner,  H.,  on  origin  of  Marquette 

ores,  135. 
Creede,  Colo.,  393. 

Crescent  mine,  Utah,  lead-silver,  375. 
Cretaceous  system,  5. 
Crimora,  Va.,  manganese,  418. 
Cripple  Creek,  Colo.,  300. 
Cripple  Creek,  Va. ,  iron  ores,  102. 
Crismon    Mammoth     copper     mine, 
Utah,  221. 

Lead-silver,  275. 
Crittenden  Co.,  Ky.,  lead  and  zinc 

ores,  239. 
Crosby,  W.  O  ,  on  joints,  15. 
Cross,  W.,  Bassick  mine,  297. 

Map  of  Telluride,  Colo.,  290. 

Pike's  Peak  deposits,  304. 
Crustification,  47. 
Cuba,  iron  mines,  1 86. 
Cumberland  mine,  Mont. ,  320. 
Cumberland  iron  mine,  R.  I. ,  173. 


Cumberland,  R.  I.,  peridotite,  56,  61. 
Curry  Co. ,  Ore. ,  gold  gravels,  348. 
Curtis,  J.  S.,  44,  46. 

Eureka,  Nev.,  277. 

Metasomatic  interchange,  32. 

Silver  in  porphyry,  35. 
Gushing,  H.  P.,  discovery  of  augite 

syenites,  161. 
Custer  Co.,  Colo.,  296. 

Idaho,  324. 
Custer  mines,  Idaho,  325. 


Dacy  Flat,  S.  D.,  313. 

Dade  Co.,  Mo.,  69. 

Dahlonega,  Ga.,  gold  deposits,  377. 

Dakota  stage,  5. 

Dall,  W.  H.,  on  Alaska,  388. 

Daly  West  mine,  Utah,  329. 

Dana,  J.  D.,  on  limonites  of  N.  Y., 

105. 
Daubree,  on  joints,  15. 

Tin  ores,  70. 

Water  in  rocks,  27,  28. 
Davidson,  Mt.,  Nev.,  340. 
Davis  Creek,  Va.,  108. 
Davison  Co. ,  N.  C. ,  lead  deposits,  238. 
Dawson,  G.  M.,  388. 

Kootenay  Lake,  rock  series,  394. 

Origin  of  gold,  Alaska,  375. 
Day,  John,  stage,  5. 
Deadwood  Gulch,  S.  D.,  310. 
Dean  iron  mines,  N.  Y.,  167. 
Dease  Lake,  gold  mines,  Alaska,  394. 
Deep  Creek,  Utah,  lead-silver  mines, 
275. 

Silver  and  gold  mines,  332. 
Deep  gravels,  California,  354. 
Deep  River,  N.  C. ,  iron  ores,  109. 
Deep  River  stage,  5. 
Deer  Lodge  Co.,  Mont.,  319. 
Deer  Trail  mine,  Utah,  333. 
De  la  Beche,  on  formation  of  veins,  53. 
De  Launay,  L. ,  on  vein  fillings,  38. 
Delaware,  chromite,  414. 
Del  Norte  Co. ,  Cal. ,  chromite,  415. 
Deloro,  Can.,  arsenic  mine,  412. 
Dent  Co.,  Mo.,  iron  ores,  123. 
Devereux,   W.    B.,    gold    gravels  of 
Black  Hills,  311. 

Magnetites  of  Colo. ,  70. 
Devonian  system,  4. 
Diadem  Lode,  Cal.,  368. 
Diamond  Hill  mines,  Mont.,  319 
Dike,  defined,  12. 

Diller,  J.  S.,  on  Cascade  Range,  Cal., 
349. 

Geology  of  Sierras,  Cal.,  359. 

Gold;  Minersville,  Cal ,  369. 

Lead  and  zinc,  Ky.,  239. 


4G8 


INDEX. 


Diller,  J.  S.,  on  Nickel  ores,  origin  of, 

439. 

Sandstone  dikes,  450. 
Dillsburg  mines,  Penn.,  179. 
d'Invilliers,  E.  V.,  on  Big  Hill  mine, 

Penn.,  178. 
Disseminated  ores,  57. 
Dodge  Co.,  Wis.,  iron  ores.  114. 
Doe  Run  Mo.,  lead  mines,  328. 
Dolomitization,  33. 
Dolores  Co. ,  Colo. ,  gold  and  silver,  287. 
Dona  Ana,  Co.,  N.  M.,  260. 
Don,  J.  R. ,  on  Australian  gold  Depo- 
sits, 383. 

Occurrence  of  gold  in  sea  water, 
373. 
Donald,  J.  T.  on  chromite,  416. 
Douglass  Island,  Alaska,  365,  390. 
Douglass,  James,    on  Bisbee  Copper 

ores,  317. 
Drinker,  H.  S.,  zinc  ores  of  Penn., 

351. 
Drumlummon  mines,  Mont.,  330. 
Dry  Canon  mines,  Utah,  375,  330. 
Ducktown,  Tenn.,  51,  103. 

Chalcopyrite  mines,  190. 

Pyrite  mines,  184. 
Dutchess  Co.,  N.  Y.,  limonites,  101. 
Dutton,  Capt.  C.  E. ,  on  geology  of  N. 

M.,  284. 
Dyestone  iron  ore,  114. 


Eagle  Co.,  Colo.,  294. 

Eagle  Hill,  porphyry,  Utah,  330. 

Eagle  River,  Colo.,  268. 

Eakins,  L.  G. ,  on  eruptive  rocks,  35. 

East  Tenn.,  mine,  192. 

East  Tintic  district,  Utah,  limonite, 

100. 
Eastern  sandstone,  Keweenaw  Point, 

Mich.,  205. 
Egan  Canon,  Nev.,  339. 
Egleston,  T.,  on  solubility  of  gold,  372. 
El  Dorado  Co.,  Cal.,  363. 
Electrical  activity  of  veins,  52. 
Elizabethtown,  N.  Y.,  172. 
Elk  Mt.,  Colo.,  iron  ores,  170. 
Elkhorn  mine,  Mont.,  58,  317. 
Elko  Co. ,  Nev. ,  silver  ores,  340. 
Elmore  Co.,  Idaho,  325. 
El  Paso,  Texas,  tin  ores,  444. 
Ely  copper  mine,  Vt. ,  190. 
Ely,  Minn.,  iron  ores,  144,  150. 
Emma  mine,  Utah,  375. 
Emmons,  S.  F.,  on  Bassick  mine  ores, 
297. 

On  Butte  copper  ores,  197. 

On  contact  deposits,  67. 

On  hematite  ores,  134. 


Emmons,  S.  F. ,  on  Lead-silver  ores  of 

Colo.,  370,  373. 

On  Leadville  ores,  363.  365. 

On  metasomatic  interchange,  33. 

On  replacements,  44. 

On  silver  ores,  35. 
Endlich,    F.    M.,    on  gold    mines  of 

Colo.,  388. 
Enriquita  mercury  mine,  Cal. ,  436. 
Enterprise,  Miss. ,  iron  ores,  109. 
Eocene  series,  5. 
Esmeralda  Co. ,  Nev. ,  340. 
Eureka,  Nev.,  35,  51. 

Aragonite,  46. 

Lead-silver  ores,  377. 

Silver  and  gold,  339. 
Europe,  mercury  of,  434. 
Eutaw  stage,  5. 
Evans  nickel  mine,  Ont.,  436. 
Evigtok,  Greenland,  aluminum,  403. 
"Ewige  Teufe",  36. 
Fahlbands,  defined,  73. 

Related  to  zones,  17. 
Fairbanks,  H.  W.,  on  Cal.,  gold  depo- 
sits, 359,  367. 

Tin  deposits,  443. 
Parish,  J.  B.,   on  veins  at  Newman 

Hill,  Colo.,  390. 
Faults.  17-35. 
Fayette  Co.,  Penn.,  108. 
Felch  Mt.,  district  Mich.,  139. 
Fergus  Co.,  Mont.,  333. 
Finlay,  J.  R. ,  on  iron  ores  of  Penokee- 

Gogebic,  144-150. 
Flagstaff  mine,  Utah,  375. 
Flathead  Co.,  Mont.,  321. 
Flat  River  district.  Mo.,  228. 
Floetze,  defined,  55. 
Florence  mines,  Mich.,  138. 
Floridian  stage,  5. 
Flucan,  defined,  49. 
Foerste.  A.  F.,  on  Clinton  ores,  120. 
Folds,  defined,  11,  12. 
Forest  Queen  mine,  Colo.,  294. 
Formation,  defined,  6. 
Fortuna  mine,  Ariz.,  337. 
Forty  mile  series,  388. 
Foster,  on  iron  ores  of  Mich. ,  135. 
Foumet's  series,  66. 
Fox  Hill  stage,  5. 

Franklin  copper  mines,  Mich. ,  208. 
Franklin   Co.,    Mo.,    lead    and    zinc 

mines,  239. 
Franklin,  Co.,  Va.,  magnetite,  169. 
Franklin  Furnace,   N.  J.,  iron  ores, 

167. 
Franklin  Furnace,  N.  J.,  Zinc  251-257. 
Frazer,  P.,  on  Penn.  limonites,  104. 
Frederick  Co. ,  Md. ,  limonites,  102. 
Fremont  Co. ,  Colo. ,  magnetite,  170. 


INDEX. 


469 


French  Creek  mines,  Penn. ,  179, 

Friedensville  zinc  mines,  Penn. ,  250. 

Frisco,  Utah,  276. 

Fritz  Island  mine,  Penn.,  179. 

Frost  Drift,  N.  C,  377. 

Fuchs,  E.,  on  useful  minerals,  461. 

Fttnter's  Bay  Alaska,  gold,  392. 

C. 

Gagnon  mine,  Butte,  Mont.,  201. 
Galena     (town),   S.    D.,     lead-silver 

mines,  272. 
Galvanic  action  in  veins,  52. 
Gangue,  defined,  55. 

Minerals,  33. 
Gap  mine,  Penn. ,  62,  65. 

Nickel  ore,  429. 

Pyrite  ore,  184. 
Gasconade  sandstone.  Mo.,  122. 
Gatling  arsenic  mine,  Ont. ,  412. 
Gay  Head,  Mass.,  109. 
Genesee  antimony  mine,  Nev.,  411. 
Genesee  stage,  5. 

Genth,  F.A.,  on  Boulder  Co.,  Colo.,  306. 
Geological  classification,  4. 
Geology,  general  principles,  3. 
Georgetown,  Colo.,  306. 
Georgia,  bauxite,  404,  408. 

Clinton  ore,  114,  117. 

Gold  ore,  379. 

Limonite,  103. 

Manganese,  418,  420. 
Georgian  stage,  4. 
Geyser  mine,  Colo. ,  30. 
Giants  Range,  Minn. ,  151. 
Gibbonsville,  Idaho,  324. 
Gila  River,  N.  M.,  Aluminum  depo- 
sits, 407. 
Gilbert.  G.  K.,  on  faults,  18. 
Gilpin  Co.,  Colo.,  47,  305,  306. 

Copper  ores,  203. 
Glacial  series,  5. 

Glenariff,  Ireland,  aluminum  ores, 407. 
Glendale,  Mont.,  lead-silver  deposits, 

273,  317. 
Glenn,  Wm.,  analyses  chromite,  414. 
Globe  district,    Ariz.,   copper    ores, 
218,  219. 

Gold  and  silver  ores,  335. 
Gogebic  Range,  Mich. ,  69. 

Manganese  ores,  422. 
Golconda,  Nev.,  manganese  ores,  421. 
Gold,  Alaska,  392. 

Analysis  of  minerals  containing, 
281. 

Chemical  reactions  in  precipita- 
tion. 371. 

Classification  of  gravels,  361. 

Deposits,  general  examples,  280. 

Gravels,  353,  354,  393. 


Gold,  introductory,  280. 

Quartz  veins,  362. 

Statistics,  401. 
Gold  Hill,  Colo.,  305. 
Good  Night  stage,  5. 
Gossan,  defined,  51. 
Gothic  district,  Colo.,  294. 
Gouge  defined,  49. 
Graham  Co. ,  Ariz. ,  336 
Grampian  Mt. ,  Utah,  276. 
Grand  Canon  of  Ariz. ,  334. 
Granite  Co. ,  Mont. ,  319. 
Granite  Mt.  mine,  Moxit. ,  319. 
Grant  Co.,  N.  M.,  silver  and  gold  ores, 

285, 
Grant  Co.,  Ore.,  gold  mines,  348. 
Grant,  U.  S. ,  on  Rainy  Lake  district, 

384. 
Grassy  Hill,  Penn.,  175. 
Great  Basin,  445. 

Arizona,  334. 

California,  349. 

Nevada,  337. 

Oregon.  347. 

Utah,  328. 
Great  Eastern  mercury  mine,  Cal. , 426. 
Great  Falls,  Mont. ,  iron  ores,  90,  109. 

Gold  and  silver,  321. 
Great  Valley,  101,  102. 

California,  445. 
Great  Western  mercury  mine,  CaL, 

426. 
Greenbrier  Co.,  W.  Va.,  hematites,  121. 
Green-eyed  Monster  mine,  Utah,  333. 
Greenland,  aluminum,  403. 
Gregory  Company,  Mont. ,  273. 
Greisen,  defined,  70. 
Gresley,  W.  S. ,  on  Mich,  iron  ore,  138. 
Griffin,  P.  H.,  on  Canada  bog  ore.  90. 
Grimm,  J.,  on  scheme  of  classifica- 
tion, 455. 
Groddeck,  A.  von,  73. 

On    scheme  of  classification    of 
ore  deposits,  456. 
Groundwater,  27. 
Guadaleazar,  Mex.,  mercury,  424. 
Guadalupe  mercury  mine,  Mex.,  436. 
Guanaco,  ChiK,  gold,  34. 
Guaymas  copper  mines,  Lower  Cal., 

221. 
Guerrero,  Mex.,  hematite,  188. 
Gunnison  Co.,  Colo.,  magnetite,  170. 
Gunnison  Region,  Colo.,  silver  and 
gold,  294. 

H. 
Hade  of  a  fault,  21. 
Hague,  A.,  Comstock  Lode,  340-344. 

Formation  of  magnetites,  174. 

Hamilton,  Nev.,  gold-silver  ores, 


470 


INDEX. 


Haile  gold  mine,  S.  C,  380. 
Harzburgite,  439. 
Hall,  J.,  cited,  124. 
Hall's  Valley,  Colo.,  bog  ore,  90. 
Hamburg  zinc  mine,  N.  J. ,  252. 
Hamilton,  Nev.,  338. 
Hamilton  series  and  stage,  5. 
Hammondville,   N.    Y.,    iron  mines, 

162-165. 
Handcart  Gulch,  Colo. ,  bog  ore,  90. 
Hanging  Rock  iron  region,  Ky. ,  95. 
Hanna,  on  North  Carolina  gold  belt, 

380. 
Hanover,  N.  M.,  zinc  ores,  259. 
Harford  Co.,  Md.,  chromite,  414. 
Harney  Peak,  S.  D.,  314. 
Hartman  zinc  mine,  Penn. ,  250. 
Hartwell  iron  district,  Wyo.,  154. 
Hastings  Co.,  Ontario,  412. 
Haworth,   E.,   on  lead  and  zinc  of 

Missouri,  242. 
Hayden's  Survey,  323. 
Hayes,  C.  W.,  388. 

On  aluminum  deposits,  405. 
Head  Center  mine,  Ariz.,  43. 
Hecla  lead-silver  mines,  Mont. ,  273. 
Hecla  mines,  Mont.,  317. 
Heim,  cited,  23. 
Helena  Company,  Mont. ,  273. 
Helena,  Mont.,  320. 
Hematite,  brown,  87-106. 

Red  and  specular,  114-159. 
Henrich,  C,  on  copper  ores,  Clifton 
district  216. 

Copper  pyrite,  Tennessee,  190. 

Gold  of  New  Mexico.,  286. 
Henry  Co.,  Va.,  magnetite,  169, 
Henwood,  cited,  55. 
Herder,  von,  on  vein  fillings,  39. 
Hesse,  Germany,  bog  ore,  92. 
Hestmandjo,  Norway,  chromite,  413. 
Highland  Co.,  Ohio,  Clinton  ores,  114. 
High  or  deep  gravels,  Cal. ,  354. 
Highwood  Mt.,  Mont.,  315. 
Hillebrand,    W.,     on    Geyser    mine 
waters,  300. 

Gold  deposits  of  Cal. ,  369. 

Vanadium,  36. 
Hill,  R.  C,  Colo.,  gold,  287. 

Concentration  of  gold  in  veins, 
51. 

Iron  ores  of  Wyo.,  174. 

Mercur  mines,  332. 

Replacements,  45. 
Hill,  R.  T.,  Mex.,  iron  ores,  187. 
Hinsdale  Co. ,  Colo. ,  gold  and  silver, 

287. 
Hitchcock,  E.,  on  limonites,  100. 
Hoefer,  H.,  on  faults,  23. 
HoUister,  cited,  275. 


Homestake  mine,  Colo. ,  294. 
Homestake  mines,  S.  D.,  313. 
Honorine  mine,  Utah,  275. 
Horizon,  defined,  6. 
Horn  Silver  mine,  Utah,  276. 
Horses,  formation  of,  48. 
Huancavelica,   Peru,  mercury  mine, 

424. 
Hubbard,    L.    L.,    on  Mich.,    copper 

ores,  210. 
Hudson  Bay,  gold  deposits,  4Q. 
HudsoQ  River,  stage,  4. 
Huitzuco,  Mex.,  mercury  mines,  424 
Humboldt  Co.,  Nev.,  antimony,  411. 

Gold  and  silver  deposits,  340. 
Humboldt-Pocahontas    mine,    Colo., 

299. 
Hunt,T.  S.,  on  Canada  magnetites,  172. 
Huronian  ores,  127. 

System,  4. 
Hurst,  limonite  bank,  Va. ,  93. 
Hussak,  cited,  314. 

Ibapah  range,  Utah,  332. 
Idaho  Basin,  325. 
Idaho  City  mining  belt,  325. 
Idaho  Co.,  Idaho,  324. 
Idaho,  geology,  323. 

Copper,  222. 

Gold,  323. 

Tin,  443. 
Idaho  Springs,  Colo.,  306. 
Iddings,  J.  P.,  cited,  59. 

Comstock  Lode,  340-344. 
Idria,  Austria,  mercury,  424. 
Igneous  rocks,  defined,  6. 

As  sources  of  metallic  ores,  34, 
.  59-62. 
Illinois  lead  zinc  mines,  233. 
Impregnations,  57. 
Independence,  Colo.,  294,  305. 
India,  aluminum  ores,  410. 
International  Geological  Congress,  3. 
Inyo  Co. ,  Cal. ,  antimony  deposits,  410. 

Lead-silver  deposits,  279. 
Iowa,  iron  ores,  98, 
Lead  and  zinc  mines,  233. 
Ireland,  aluminum  ores,  407. 

Bog  ores,  92. 
Iron  Co.,   Utah,  antimony  deposits 
(411.) 

Hematites  and  magnetites,  180, 
Irons,  defined,  66. 
Iron  hat,  defined,  51. 
Iron  in  nature,  86,  87. 
IronMt.,  Colo.,  170. 
IronMt.,  Mont.,  321. 
IronMt.,  Mo.,  59,  71,  157. 
Iron  ores,  analyses,  85. 

Composition,  84,  186. 


INDEX. 


471 


Iron  ores,  Discussion  of,  85-87. 

Impurities,  85-86. 
Iron  ores,  magnetite,  160-184. 
Iron  ore  localities: 

Adirondack  Mountains,  160. 

Alabama,  104. 

Brazil,  175. 

Colorado,  98,  170-174. 

Connecticut,  101. 

Cuba.  186. 

Georgia.  103,  117.. 

Hesse,  Germany,  92. 

Ireland,  92. 

Kentucky,  95,  107. 

Clinton  ore,  114. 

Maryland,  116. 

Massachusetts,  101. 

Mexico,  187. 

Michigan,  125-150. 

Minnesota,  96,  150,  174. 

Missouri,  96,  122. 

Mississippi,  109. 

New  Jersey,  101,  160,  173. 

New  York,  114,  167. 

North  Carohna,  104-109,  160. 

Nova  Scotia,  120. 

Ohio,  96-115. 

Oregon,  92. 

Pennsylvania,  93,  104,  113. 

Tennessee,  103,  114. 

Vermont,  100,  184. 

Virginia,  114,  169. 

West  Virginia,  107,  114,  131. 

Wisconsin,  114. 

Wyoming,  171. 
Iron  ore,  pyrite,  184. 

Red  and  specular  hematite,  140- 
159. 
Iron  ores : 

Siluro-Cambrian  limonites,    100- 
106. 

Spathic,  112. 

Statistics,  186. 
Irving,  R.  D.,  cited,  205. 

Copper  ores,  origin,  209. 

"  Fimdamental  complex,"  128. 

Michigan,  ores,  127. 

Penokee  district  ores,  139. 

Replacements,  44. 
Isle  Royale  mines,  Mich. ,  207. 
Isochemic  lines,  183. 


Jackson,  C.  T.,  on  Penn.  limonites, 

104. 
Jackson  stage,  5. 
Jacksonville,  Ala. ,  404. 
Jacupiranga,  Brazil,  iron  ore,  56,  61. 
Jalisco  State,  Mexico,  hematite,  188. 
James  River,  Va.,  hematites,  154. 


Jasper  Co.,  Mo.,  lead  and  zinc  mines, 

241. 
Jefferson  Co.,  N.  Y.,  nickel  ores,  123, 

440. 
Jefferson  Co.,   Mo.,    lead   and   zinc 

mines,  239. 
Jefferson  Co.,  Mont.,  317. 
Jenney,  W.  P.,  cited,  43. 
Gold  deposits,  283. 
Lead  and  zinc  mines  of  the  Miss. 

Valley,  237,  243,  446. 
Lead  and  zinc  mines  of  Mo. ,  230, 

245. 
Joachimsthal,    Bohemia,     cited     on 

water,  31. 
John  Day  stage,  5. 
Johnson,  L.  C. ,  on  limonites,  97. 
Joints,  compression,  13,  14. 
Jones  copper  mine,  Cal. ,  196. 
Joplin,    Mo.,    zinc  and  lead  mines, 

240. 
Josephine  Co. ,  Ore. .  gold  mines,  348. 
Juab  Co.,  Utah,  330. 
Judith  Mt.,  Mont.,  315. 
Julien,  A.  A.,  on  origin  of  magnetite, 

218. 
Juniata  district,  Penn.,  Clinton  ore, 

116. 
Jurassic  system,  5. 
Jura-Trias  system,  5. 


Kadiak  Island,  Alaska,  gold  ores,  392. 
Kansas,  lead  and  zinc  mines,  240. 
Kearney  mines,  N.  Y. ,  iron  ores,  125. 
Kelley  lode,  N.  M.,  lead-silver  ores, 

260. 
Kemp,  J.  F.,  on  Iron  Mt.,  Colo.,  ores, 
174. 

On  N.  J.  zinc  deposits,  257. 

On  Tenn.  copper  deposits,  193. 
Kennedy,  W.,  on  nodular  ores,  97. 
Kentucky,  Clinton  ore,  114. 

Lead  and  zinc  ores,  239. 

Limonites,  95,  107. 
Kern  Co.,  Cal.,  antimony,  41Q. 
Kerr,  W.  C,  cited,  377. 

On  N.  C.  magnetite  ore,  169. 

On  copper  ores,  194. 
Keweenawan  svstem.  4,  166. 
Keweenaw  Point,  Mich.,  57,  204, 
Keyes,  C.  R.,  on  Mo.  lead  ores,  228. 
Kimball,    J.    P.,    on     chemistry    of 
limonites,  112. 

On  Cuban  iron  ores,  187. 

On  formation  of  iron  ores,  111, 
112. 

On  hematite,  124. 

On  magnetite,  173. 
King,  C. ,  on  Comstock  Lode,  340,  343. 


472 


INDEX. 


Kingston,    Canada,     corundum    de- 
posits, north  of,  490. 

Kittitas  Co.,  Wash.,  gold  placers,  347. 

Klamath  Mt.,  Cal.,  359. 

Klausen,  Austria,  cited,  42,  43. 

Knight,  W.  C,  cited,  174. 

On  Hartwell  iron  ores,  154. 

Knob  of  igneous  rock  defined,  13. 

Knowlton,  cited  on  Cal.  deep  gravels, 
358. 

Koehler,  G. ,  on  scheme  of  classifica- 
tion of  ore  deposits,  452. 

Kongsberg,  Norway,  cited,  73. 

Kootenai  Co. ,  Idaho,  324. 

Kootenay  Lake,  B.  C,  394, 

Kwei-Chau,  mercury  deposits,  Asia, 
424. 


Laccolite  defined,  12. 

Lager  defined,  .55. 

Lagorio,  cited  on  ore  deposits,  59. 

Lahontan  Lake,  Nev. ,  337. 

Lake  Champlain  iron  region,  160. 

Lake  Co..  Colo.,  294. 

Lake  of  the  Woods,  gold  district,  384. 

Lake  Superior,  copper  deposits,  446. 

Gold  and  silver,  283. 

Iron  deposits,  125,  446. 

Manganese  ores,  422. 
Lake  Valley,  N.  M.,  285. 
Lancaster  Co.,  Penn.,  chromite,  414. 
Lander  Co.,   Nev.,  antimony  mines, 
mines,  411. 

Gold  and  silver  mines,  339. 
Lane  and  Hayward  mines,  Alaska, 

392. 
Lane's  bismuth  mine.  Conn. ,  412. 
Lansing,  Iowa,  lead  and  zinc  mines, 

235. 
La  Plata  Co..  Colo.,  287. 
Laramie  Co.,  Wyo.,  154. 
Laramie  stage,  5. 
Lassens  Peak,  Cal. ,  349. 
Lateral  enrichments  of  a  vein,  49. 
Lateral  secretion,  40.  41,  42. 
Launay,  L.  de,  cited,  461. 
Laurentian  system,  4. 
Laur,  M.  F.,  on   occurrence  of  alu- 
minum, 404. 
Lawson,   A.   C,  on  geology  of  Cal., 
359. 

On  California  granite,  375. 

On  Rainy  Lake  gold  region,  384. 
Lead  alone,  226. 
Lead  and  zinc,  233. 
Lead  City.  S.  D.,  313. 
Lead,  production  of,  232. 
Lead  series,  226. 
Lead-silver  ores,  260-263. 


Lead  veins  in  gneiss,  226. 
Leadville,  Colo.,  cited,  17,  21,  35,  51. 

Copper  mines,  221. 

Lead-silver  mines,  262. 

Silver  ores,  265. 
Le  Conte,  J.,  on  Cal.  gravels,  356. 

On  mercury  deposits,  Cal. ,  427. 

On    scheme  of   classification  of 
ore  deposits,  450. 
Lee  Hill  mines,  Minn.,  146. 
Leesburg,  Idaho,  324. 
Lehigh  Co.,  Penn.,  iron  mines,  101, 

169. 
Lemhi  Co.,  Idaho,  324. 
Leonard,   A.   G.,   on  Lansing  mine, 
Iowa,  235. 

On  origin  lead-zinc  of  Miss.  Val 
ley,  237. 
Lesley,  J.  P.,  cited,  120. 

On  Marcellus  stage,  94. 

On  Penn.  iron  mines,  178. 
Lesquereux,  on  Cal.  gravels,  355. 
Lewis  Co.,  Mont,  320. 
Lewiston,  Mont.,  323. 
Libbey  Creek,  Mont.,  322. 
Lignitic  stage,  5. 
Limonites,  analysis,  106. 

Iron  ore,  87-106. 
Lincoln  Co.,  Nev.,  338. 
Lindgren,   W.,    on   Boise  Co.,   gold 
veins,  325. 

On  Cal.  gold  veins,  365. 

On  Cal.  gold,  occurrence,  369. 

On  Calico  district,  351. 

On  War  Eagle  claim,  397. 
Little  Annie  mine,  Colo. ,  295. 
Little  BeltMts.,  Mont.,  321. 
Little  Cottonwood  Canon,  Utah,  274. 
Little  Rock,  Ark.,  aluminum,  406. 
Livingston  Co.,  Ky.,  239. 
Llano  Co.,  Texas,  copper  mines,  204. 
Logan  Co.,  Kansas,  nickel  ores,  440. 
London  mines,  Tenn.,  192. 
Lottner-Serlo,  on  schemes  of  classifi- 
cation of  ore  deposits.  451. 
Louisa.  Co. ,  Va. ,  pyrite  mines,  184. 
Loup  Fork  stage,  5. 
Lovelock  mines,  Nev. ,  nickel,  440. 
Lovers  Pit,  Mineville,  N.  Y. ,  85. 
Low,    A.    P.,    on    Hudson    Bay  iron 

ores,  154. 
Lowell,  Mass.,  nickel  ores,  430. 
Lower  Helderberg  series,  4. 
Lower  Claiborne  stage,  5. 
Low  Moor,  Va. ,  zinc  ores,  95,  256. 
Lubeck,  Me.,  lead  mine,  227. 
Lucky  Boy  mine,  Utah,  333. 
Lyman,  B.  S.,  on  limonite,  94 
Lyndhurst,  Va.,  manganese,  418. 
Lyon  Co.,  Nev.,  340. 


INDEX. 


473 


Lyon  Co.,  Ky.,  95. 

Lyon  Mt. ,  N.  Y. ,  iron  ores,  162. 

M 

Madison  Co.,  Mont.,  316. 

MagdalenaMt.,  N.  M.,  260. 

Magna  Charta  mine,  Butte,    Mont., 

319. 
Magnetite  iron  ore,  56,  60-63, 160-181. 

Analyses,  183. 

Beds.  160. 

Origin  of  deposits,  181. 

Sands.  180. 
Maiden,  Mont.,  323. 
Maine,  copper  pyrite,  190. 

Gold,  383. 

Tin,  444. 
Manganese  ores,  416,  418. 
Mansfield  ores,  Penn.,  121. 
Marcellus  stage,  5. 
Margerie  and  Heim,  cited  on  faults, 

23. 
Maricopa  Co.,  Ariz.,  335. 
Mariposa  Co.,  Cal.,  363. 
Markhamville,  N.  B.,  manganese,  422. 
Marmora.  Can. ,  arsenic  mines,  412. 

Gold  mines,  401. 
Marquette  district,  129-136. 
Marquette  range,  69. 
Marshall  Mt.,  Colo.,  306. 
Marshall  tunnel,  Georgetown,  Colo., 

50. 
Maryland,  chromite,  414. 

Clinton  ore,  116. 

Gold  mines,  381. 

Limonite,  102. 
Mary  Co.,  Tenn.,  192. 
Marysville,  Mont.,  320. 
Marysville,  Utah,  424. 
Massachusetts,  lead  mines,  227. 

Limonite,  101. 
Mayflower  mine,  Mont.,  317. 
Maynard,  G.  W.,  on  chromite,  416. 
Mazon  Creek,  111.,  107. 
McCalley,  H.,  aluminum,  406. 
McConnell,  R.  G.,  cited,  388. 

On  Trail  Creek  rock  series,  396. 
McCreath,  A.  S.,  cited,  107. 

On  slates,  93. 
Meagher  Co.,  Mont.,  320. 
Means,  E.  C. ,  referred  to,  256. 
Medina  stage,  4 
Menominee  district,   Lake  Superior, 

135-139. 
Meramec  hematite  mines.  Mo.,  123. 
Mercur  gold  mines,  Utah,  330. 
Mercury,  occurrence  of,  424. 
Merrill,  G.  P.,  cited,  35. 
Merritt,  W.  H.,  on  Lake  of  the  Woods 
district,  385. 


Mesabi  district,  Minn. ,  134. 
Mesabi  range,  Minn.,  144. 
Mesozoic  group,  5. 
Metamorphic  rocks,  defined,  6. 
Metasomatic  defined,  32. 
Methods  of  vein  filling,  39. 
Meunier,  on  origin  of  chromium,  413. 
Mexico,  iron  ore,  187. 

Mercury,  424. 

Tin,  444. 
Mexican  mine,  Alaska,  391. 
Miask,  Urals,  aluminum,  403. 
Michigan,  copper,  204. 

Gold,  383. 

Iron,  125-150. 
Michigamme  jasper,  137.  - 
Middle  Hill,  Penn  ,  175. 
Middletown,  Conn.,  lead^lpaine,  227. 
Midway  stage,  5. 
Milan,  N.  H. ,  pyrite  mine,  184. 
Miller,    Prof.,    on    Kingston,     Ont.j 

aluminum,  409. 
Mine  Hill,  Cal.,  358. 
Mine  Hill.  N.  Y. ,  zinc  mine,  252. 
Mine  la  Motte,  Mo.,  cited,  58,  69. 

Lead,  228. 

Nickel,  429,  440. 
Mineral  Hill,  Colo.,  302. 
Mineville,  N.  Y..  72,  85. 
Mine  waters,  52. 
Mining  laws,  447. 
Minnesota  copper  mines,  212. 

Iron  ore,  Mesabi  range,  150. 

Limonite,  96. 

Magnetite,  174. 
Miocene  series,  5. 
Mississippi  Valley,  19,  446. 

Iron  ores,  109. 

Lead  and  zinc,  231,  233. 
Mississippian  series,  5. 
Missoula  Co.,  Mont.,  321. 
Missouri,    Cambrian    red    hematite, 
122. 

Copper,  213. 

Lead  ores  of  southeastern  Mo., 
228. 

Limonite,  96. 

Red  hematites,  122. 

Tin,  445. 

Zinc  and  lead  in  the  southwest, 
240. 
Moericke,  cited,  34. 
Mohave  Co.,  Ariz.,  335. 
Moisie,  Can.,  magnetite  sands,  181. 
Monarch  district,  Colo.,  268. 
Monheim,  V.,  on  zinc  ores  of  Stol 

berg,  257. 
Monocline  defined,  11,  19. 
Mono  Co.,  Cal.,  352. 
Monroe,  Conn.,  bismuth,  412. 


474 


INDEX. 


Montalban  series,  4. 
Montana,  geology  of,  314 

Copper,  203. 

Lead-silver,  273. 

Silver  and  gold,  314 

Tin,  443. 
Montana  stage,  5. 
Monte  Cristo  mine,  Wash.,  arsenic, 

412. 
Moore,  P.  N.,  on  iron  ores,  109. 
Morenci,  Ariz. ,  copper  district,  215. 
Morozewicz,  J.,  cited  173. 

On  laws  of  separation  of  ores, 
62,  63. 
Mosquito  range,  Colo. ,  262. 
Mother  Lo(^  of  California,  363. 
Mount  Baldk^,  Utah,  333. 
Mount  DavMson,  Nev. ,  340. 
Mount  HopI,  N.  J.,  167. 
Mount  Marshall,  Colo. ,  306. 
Mount  McClellan,  Colo.,  295. 
Mount  Prometheus,  Nev.,  339 
Mount  Shasta,  Cal,  349. 
Mule  Pass,  Mt.,  Ariz.,  217. 
Mullica  Hill,  N.  J.,  89. 
Munroe,  H.  S.,  cited  71. 

On  limonites,  41. 

On    scheme    of  classification  of 
ore  deposits,  457. 
Murphee's  Valley,  Ala.,  120. 
Murray  nickel  mine,  Ont. ,  436. 


Nacemiento  copper  mines,  N.  M.,  334. 
Nason,  F.  L.,   on  geology  of  Ring- 
wood  mines,  169. 

On  N.  J.  zinc  deposits,  252,  257. 

On  Mo.  iron  ores,  158. 
Neal  district,  Idaho,  323. 
Neck  of  igneous  rock  defined,  12. 
Neihart  mining  district,  Mont.,  320. 
Nelson  Co.,  Va.,  tin  ore,  444. 
Nelson,  B.  C,  gold,  394. 
Neocene  system,  5. 
Nevada,  antimony  mines,  411. 

Geology  of,  337. 

Gold  and  silver  deposits,  338. 

Mercury,  424. 

Nickel,  440. 
New  Almaden,  Cal. ,  mercury,  425. 
Newberry,  J.  S.,   on  copper  deposits 
of  N.  M.,  and  Utah,  224 

On  iron  ore,  120. 

On  lead- silver  deposits,  Utah,  276. 

On  Silver  Reef,  Utah,  333. 

On   schemes  of  classification  of 
ore  deposits,  453. 
Newberry,  W.  E. ,  on  Colorado  mines, 
271. 


New  Brunswick,  N.  J.,  copper  mines, 

190. 
New  Caledonia  nickel,  439. 
Newfoundland,  chromite,  416. 

Copper,  190. 
New  Hampshire,  lead  mines,  227. 

Tin,  444. 
New  Idria  mines,  Cal.,  426. 
New  Jersey,  copper  ores,  223. 

Gold  ores,  383. 

Iron  mines,  173. 

Limonite,  101. 

Magnetite,  160. 

Zinc  mines,  253. 
New  Jersey,  Greensand  stage,  5. 
New    Jersey    Zinc    and    Iron    Co.'s 

mines,  252,  254. 
Newman  Hill.  Col.,  24,  47,  50. 

Mines  of,  338. 
New  Mexico,  aluminum  deposits,  407. 

Copper,  224,  334. 

Geology  of,  284. 

Lead-silver,  260. 

Silver  and  gold,  285. 

Zinc  ores,  259. 
New  River,  Va. ,  limonite.  103. 
Newton,  Cal.,  copper  ore,  196. 
Newton  Co. ,  Mo. ,  zinc  mines,  240. 
New  York  copper  mine,  Ariz. ,  219. 
New  York,  CUnton  ore,  114,  120. 

Gold  deposits,  383. 

Iron  mines  of  the  Highlands,  167. 

Iron  ore  of  Adirondacks,  166. 

Lead  mines,  227. 

Limonite,  101,  105. 
NeyCo.,  Nev.,  338. 
Nez  Perces  Co. ,  Idaho,  324. 
Niagara  series  and  stage,  4. 
Nicholas,    W.,    on   precipitation    of 

gold,  373. 
Nicholson,   F.,    on    Missouri    copper 

mines,  214. 
Nickel,  Arkansas,  440. 

Nevada,  440. 

Norway,  431. 

Ores,  table  and  general  remarks, 
428,  429. 
^      Ores  of  igneous  origin,  61,  64. 

Pennsylvania,  439. 
Niobrara  stage,  5. 

Northampton,  Mass. ,  lead  mines,  227, 
North  Carolina,  aluminum,  407. 

Copper,  194. 

Gold,  376,  380. 

Limonite,  104-109. 

Magnetite,  160,  174. 

Nickel,  439. 

Specular  ores,  155. 

Tin,  444. 
Northern  States,  gold  deposits,  381. 


INDEX. 


475 


Northwest  Territory,   gold  deposits, 

393. 
Norway,  chromite,  413. 
Nova  Scotia,  Clinton  ore,  120. 

Copper  pyrite,  190. 

Gold,  397. 


Oat  Hill,  Cal. ,  mercury  mine,  426. 
Ocean  as  a  source  of  ores,  33. 
Ogdensburg,  N.  J.,  250. 
Ohio,  Chnton  ore,  114,  115. 

Limonite,  96,  107. 
Okanogan  Co.,  Wash.,  347. 
Old   Dominion    copper  mine,   Ariz., 

219. 
Old  Sterling  mine,  Mo.,  125. 
Old  Tenn.  mine,  192. 
Oligocene  series,  5. 
Oliver  mine,  Va.,  152. 
Olmstead,  I.,  on  Burden  mines,  111. 
Oneida  Co..  Idaho,  327. 
Ontario,  arsenic  mine  at  Deloro,  412. 

Nickel  mine,  436. 
Ontario  mine,  Utah,  329. 
Ontonagon    copper    district,    Mich., 

207,  209. 
Ophir  Canon.  Utah,  275,  330. 
Ophir  silver  mine,  Cal. ,  353. 
Oppel,  von   on  strata  beds,  55. 
Oquirrh  Mt.  mines,  Utah,  274. 
Orange  Co. ,  N.  Y. ,  zinc  mines,  256. 
Orchard  gneiss,  162. 
Ore  deposits,  classification,  54. 

Literature  on,  74-79. 
Ore -minerals,  33. 
Oregon,  geology  of,  347. 

Gold  mines,  348. 

Mercury,  424. 
Organic    matter   as  a   precipitating 

agent,  68. 
Oriskany  series,  4. 
Orton,  E.,  on  black  band  ore,  108. 

On  dolomitization,  32. 
Ouachita  uplift,  446. 
Ouray  Co.,  Colo.,  287. 
Owyhee  Co.,  Idaho,  35,  327. 
Ozark  uplift,  122,  155. 


Pacific  Ocean,  445. 
Pahranagat  district,  Nev.,  338. 
Paleozoic  group,  4. 
Palo  Duro  stage,  5. 
Panama  manganese,  423. 
Panamint  district,  Cal.,  352. 
Park  Co.,  Colo.,  295. 
Parting  in  a  vein,  defined,  49. 
Passaic  iron  belt,  N.  J. ,  167. 
Patton  mines,  Ore. ,  bog  ore,  90. 


Peale,  A.   C,  on  Montana  gold  de- 
posits, 315. 
Pearce  mine,  Ariz.,  silver  and  gold, 

336. 
Pearce,  R.,  Colo.,  gold,  306,  365. 

On  gold  with  pyrite,  372. 
Pechin,  E.  C,  cited,  95. 
Peekskill,  N.  Y.,  aluminum  ores,  410. 

Magnetite,  172,  173. 
Penfield,  S.  L.,  cited,  441. 
Pennsylvania,  brown  hematites,  93, 
94,  101. 

Chromite,  414. 

Clinton  ore,  116. 

Gold,  383. 

Lead  mines,  227. 

Limonite,  101,  104. 

Mansfield  ore,  121. 

Spathic  ore,  112. 
Penokee-Gogebic  district,  Mich. ,  139. 
Penrose,  R.  A.  F.,  on  Arkansas  iron 
ores,  96. 

On    Arkansas    manganese    ores, 
420. 

On  Colorado  gold  deposits,  304. 
Pentlandite,  429. 
Percival,   on   Connecticut   limonite, 

104. 
Permian  series,  5. 
Perry  Co.,  Penn.,  108. 
Peru,  S.  A.,  mercury,  424. 
Peters,  cited,  437. 
Phelps  Co. ,  Mo. ,  iron  ores,  123. 
Phillips,  J.  A.,  on  scheme  of  classifi- 
cation of  ore  deposits,  454. 
PhiUipsburg,  Mont.,  319. 
Phoenix  copper  district,  Mich. ,  208. 
Phosphorus  in  iron  ore,  85,  183. 
Pictou  Co.,   Nova  Scotia,   iron  ore, 

120. 
Pierre  stage,  5. 
Pike's  Peak,  Colo.,  403. 
Pilot  Knob,  Mo. ,  iron  ores,  155. 
Pima  Co.,  Ariz.,  lead-silver,  279. 

Silver  and  gold,  336. 
Pinal  Co.,  Ariz.,  gold  and  silver,  335. 
Pinches  in  a  vein,  49. 
Pioche,  Nev.,  338. 
Pirsson,  on  geology  of  Little  Rocky 

Mts.,  322. 
Pitch  of  a  fold  defined,  12. 
Pitkin  district,  Colo,  294. 
Pittsburg  iron  ore  group,  108. 
Pittsburg  seam,  108. 
Piute  Co.,  Utah,  333. 
Placer  Co.,  Cal.,  chromite,  415. 

Magnetite,  171. 
Placers,  59,  70. 

Plateau  region  of  Rockies,  445. 
Platinum,  441. 


476 


INDEX. 


Platoro,  Colo.,  296. 

Pleistocene  system,  5. 

Pliocene  series,  5. 

Point  Orford.  Ore.,  348. 

Poorinan  lode,  Idaho,  327. 

Portage  Lake  copper  mines,  Mich., 

207. 
Portage  stage,  5. 
Port    an    Port  Bay,    Newfoundland, 

chromite,  416. 
Porter,  J.  B.,  on  Clinton  ore,  120. 
Porter,  J.  A.,  on  Colo,  gold,  288. 
Portland  mines.  Cripple  Creek,  Colo. , 

305. 
Posepny,  F.,  cited,  47,  376. 

On  contact  deposits,  67. 

On  ore  origin,  459. 

On  replacement,  44. 
Potrillos,  Mex.,  tin  ores,  444, 
Potomac  formation,  5. 
Potsdam  stage,  4. 
Power,  F.  D.,  on  classification  of  ore 

deposits,  56,  461. 
Pratt,  J.  H.,  on  chromite,  61. 

On  North  Carolina  chromite,  413. 

On  origin  corundum,  408. 
Prescott,  Ariz.,  220. 
Prime,  F. ,  on  Siluro-Cambrian  limon- 
ites,  94,  104. 

On  classification  of  ore  deposits, 
451. 
Prometheus  Mt.,  Nev.,  339. 
Prosser  mines,  Ore.,  bog  ore,  91. 
Psilomelane,  416. 
Puei'co  stage,  5. 
Puget  Sound,  90. 
Puget  Sound  Basin,  Wash.,  346. 
Pumpelly,  R. ,  on  classification  of  ore 
deposits,  456. 

On  copper  rock  of  Michigan,  309. 

On  hematite,  122. 

On  replacements,  44. 
Putnam,  B.  W.,  cited,  72. 

On  magnetite  ore,  165. 
Putnam  Co.,  N.  Y.,  iron  mines,  166. 
Pyrite  beds,  184. 

With  copper,  189. 
Pyrrhotite,  of  igneous  origin,  61,  64, 
65. 

With  nickel,  430. 
Pyrolusite,  416. 


Quaco  Head,  N.  B.,  manganese,  422. 
Quaquaversal,  defined,  12. 
Quartzburg  Grimes  Pass  belt,  325. 
Quaternary  system,  5. 
Queen  of  the  West  mine,  Colo.,  266. 
Quicksilver,  424. 


Quigley,  Mont.,  321. 
Quincy  mines,  Mich.,  2( 
Quinnesec  mines,  Mich. 
Quebec,  chromite,  416. 
Copper  mines,  190. 


138. 


Raibl,  Austria,  lead-silver  deposits,  44. 

Rainbow  lode,  Mont.,  319. 

Rainier  Mt.,  346. 

Rainy  River  gold  district,  Minn. ,  383. 

Rampart  Series  in  Alaska,  388. 

Ramshorn  mine,  Idaho,  324. 

Randsburg  gold  mines,  Cal.,  351. 

Raritan  stage,  5. 

Rathgeb  mine,  Cal. ,  370. 

RavaUiCo.,  Mont.,  321. 

Raven  Hill,  Colo.,  305. 

Raymond  &  Fly  mine,  Nev.,  838. 

Recent  series,  5. 

Red  Cliff,  Colo.,  294. 

Red  Mt  ,  Ala.,  117. 

Red  Mt.,  Kern  Co.,  Cal..  352. 

Red  Mt.,  Ouray  Co,,  Colo.,  272. 

Red  Rock,  San  Francisco,  manganese, 

421. 
Reese  River  district,   Nev.,    banded 
veins,  47. 

Gold  and  silver,  339. 
Reich,  on  electrical  action  in  veins,  52. 
Replacement,  32,  44,  58. 
Republic  mine,  Mich. ,  85. 
Residual  clay  in  a  vein,  49. 
Residual  deposits,  59,  71. 
Rhode  Island,  gold  deposits,  383. 
Richmond,  Mass.,  limonites,  101. 
Richthofen,  von,  on  California  gold 
veins,  365. 

On  origin  Comstock  lode,  340-341. 
Rickard.T.  A.,  on  California  gold,  370. 

On  Newman  Hill,  Colo.,  292, 
Rico,  Colo.,  lead-silver,  271. 
Riddle's,  Oregon,  nickel,  438. 
Rifting  in  granite,  13,  15. 
Rio  Grande  Co.,  Colo.,  295. 
Rio  Tinto,  Spain,  old  timbers,  52. 
Rio  Viento  Frio,  S.  A.,   manganese 

423. 
Ripley  stage,  5. 
River  gravels  with  gold,  353. 
Roanoke,  Va.,  zinc  ores,  249. 
Roaring  Fork  Creek,  Colo. ,  268. 
Robert  E.  Lee  mine,  Colo.,  263. 
Robinson  mine,  Colo.,  266. 
Rochester,  Mont.,  317. 
Rockbridge  Co. ,  Va. ,  tin  ores,  444. 
Rock  Creek  district,  Idaho,  325. 
Rocks,  classified,  6. 

Eruptive,  447. 

Magmas,  60-67. 


INDEX. 


471 


Eocky  Mts.,  faults  of,  20. 

Lead  and  zinc  deposits,  249. 

Silver  and  gold  deposits,  308. 
Eogers,  H.  D.,  cited,  120. 

On  New  Jersey  zinc  deposits,  251. 
Rolker,  C.  M.,  on  Silver  Reef  ores, 

334. 
Ropes  gold  mine,  Mich. ,  383. 
Rosenbusch,  H.,  cited,  59. 
Rosita.  Colo.,  296. 
Rossland.  B.  C,  62,  396. 
Roth,  J.,  on  analyses  igneous  rocks, 87. 
Rothwell,  R.  P. ,  on  Silver  Reef  ores, 

333. 
Rotten  limestone  stage.  5. 
Roubidoux  sandstone.  Mo.,  122. 
Routirara,     Sweden,     magnetite,    6, 

172,  175. 
Roxbury,  Conn.,  limonite,  112. 
Ruby  mine,  Colo.,  317. 
Russell,  I.  C. ,  on  Clinton  ore,  120. 
Russia,  platinum,  441. 
Rye,  N.  Y.,  bog  ore,  91. 

S 

Sacramento  Valley,  Cal. ,  349. 
Safford,  J.  S.,  on  siliceous  group,  96. 

On  Tennessee  limonites,  103. 
Saguache  Co. ,  Colo. ,  293. 
Sain  Alto,  Mex. ,  tin.  444. 
Salina  Co. ,  Ark. ,  nickel  ore,  440. 
Salina  series,  4. 

Salisbury,  Conn.,  limonites,  101. 
Salt  Co..  Utah,  329. 
San  Benito  Co. ,  Cal. ,  antimony,  410. 
San  Bernardino  Co.,  Cal.,  iron  ore. 

171. 
Sandberger,     F.,    on    derivation    of 

ores,  34,  41. 
On  dark  silicates,  447. 
San  Diego  Co.,  Cal.,  iron  ores,  171. 
San  Emigdio,  Cal. ,  antimony,  410. 
Sangre  de  Cristo  Range,  Colo.,  260- 

300. 
San  Joaquin  Co.,    Cal.,   manganese, 

421. 
San  Juan  Mt. ,  287» 
San  Juan  Co.,  Colo.,  bismuth,  412. 

Gold  and  silver,  287. 
San  Luis  Obispo  Co.,  Cal,  chromite, 

415. 
San  Miguel  Co..  Colo.,  290. 
Sante  Fe  Co..  N.  M.,  286. 
Santa  Rita  copper  district,  N.  M.,  219. 
Santa  Rita  Mt.,  N.  M.,  285. 
Santiago,  Cuba,  iron  ores,  186,  187. 
Saucon  Valley,  Penn. ,  zinc  mines,  58, 

250. 
Sawatch  Mt.,  Colo.,  262. 
Schapbach,  cited,  42. 


Schemes  of  classification  of  deposits. 

448-457. 
Schmidt,  A.,  on  Missouri  iron  ores, 
122,  158. 

On  Missouri  lead  and  zinc  ores, 
242,  246. 

On  replacement,  44. 
Schrauf,   A.,   on    mercury  deposits, 

425. 
Schoharie  stage,  5. 
Schuyler  copper  mines,  N.  J. ,  233. 
Secondary  alteration  in  veins,  50. 
Sedimentary  rocks  defined,  6. 
Segregation,  59,  72. 
Selvage  in  a  vein  defined,  49. 
Servia,  mercury,  424. 
Seven  Devils'  district,  Idaho,  222. 
Sevier  Co.,  Ark.,  antimony,  411. 
Shaler,    N.  S.,  on  origin  of  Clinton 

ore,  120. 
Shasta  Co.,  Cal.,  chromite,  415. 
Shasta  Mt.,  Cal.,  349. 
Shasta  stage,  5. 
Shaw  mine,  Cal.,  369. 
Shaw  Mt.  district,  Idaho,  325. 
Shear  zones  defined,  17,  58. 
Sheep  Creek  Basin,  Alaska,  393. 
Sheep  Mt.  district,  Idaho,  324. 
Sheerer,  cited,  430. 
Sheet  defined,  12. 
Shepherd  Mt.,  Mo.,  157. 
Sherbrooke,  Quebec,  190. 
Siderite,  genetic  relations,  112. 

Spathic  ore,  106-113. 
Sierra  Co.,  Cal.,  iron  ore,  171. 
Sierra  de  Mercado,  Mex.,  hematite, 

188. 
Sierra  Nevada  Range,  Cal.,  geology 

of,  349,  358. 
Siluro-Cambrian  limonites,  100-105. 
Silver  and  gold  ores,  analyses,  281. 

Deposits.  280. 

Statistics,  401. 
Silver  Bow  Basin,  Alaska,  391. 
Silver  Bow  Co.,  Mont.,  318. 
Silver  Bow  Creek,  Mont.,  197,  319. 
Silver,  Cahfornia,  351. 
Silver  City,  N.  M.,  407. 
Silver  Cliff,  Colo.,  57,  296. 
Silver  Islet,  42,  283. 
Silver  King  mine,  Ariz.,  335. 
Silver  minerals,  281. 
Silver  Plume,  Colo..  306. 
Silver  Reef,  Utah.  333. 
Silverton,  Colo.,  293. 
Silver,  Washington,  347. 
Simmon's  iron  mines.  Mo.,  123. 
Simundi.  H. .  on  gold  ores,  35. 
Sitka,  Alaska,  392. 
Slickensides  or  slips  defined,  23. 


478 


INDEX. 


Slocan  gold  district,  B.  C,  394. 
Smithfield  iron  mine,  Colo.,  170. 
Smith,  F.  C,  on  Black  Hills  gold  de- 
posits, 313. 
Smith,   J.   P.,   on  auriferous  strata, 

374. 
Smuggler  mine,  Colo. .  289. 
Smuggler  Mt.,  Colo.,  270. 
Smyrna,  alumimmi,  410. 
Smyth,  C.  H.,  Jr.,  on  hematite,  121, 
124,  125. 

On  limonites,  113, 
Smyth,  H.  L.,  139. 

On    Menominee   district    mines, 
136.  138. 

On  Michigan  copper;  210. 

On  Michigan  iron  ores,  127,  144. 
Snake  River,  Idaho,  273,  323. 
Snohomish    Co.,   Wash.,   silver    de- 
posits, 347. 
Socorro  Co, ,  N.  M. ,  gold  and  silver, 

285. 
Sonora,  Mex.,  antimony,  411. 
Soret's  principle,  64,  171. 
Sources  of  the  metals,  33,  34. 
.South  Carolina,  gold  deposits,  380. 
South  Dakota,  gold  and  silver  ores, 
309. 

Lead-silver,  272. 

Tin,  442. 
Southern  States,  gold,  446. 

Pyrite  under  gold,  184. 
South  Mt.,  Penn.,  iron  ores,  166,  169. 

Gold  belt,  378. 
South  Park,  Colo.,  295. 
Spanish  Peaks,  Colo. ,  295. 
Spathic  iron  ore,  112. 
Spenceville,  Cal.,  copper  mine,  195. 
Sperry,   F.    L.,    on  Algoma  district, 

441. 
Spenylite,  438. 
Spurr,  J.  E.,  on  Aspen,  Colo.,  269. 

On  iron  ores,  152. 

On  Mercur  gold  deposits,  331. 

On  Mesabi  ores,  152. 

On  Yukon  Basin,  388. 
St.  Frangois  Co. ,  Mo. ,  lead  and  zinc, 

239. 
St.  Genevieve,  Mo.,  copper  mines,  213. 
St.  Lawrence  Co.,  N.  Y.,  lead  mines, 

226. 
St.  Louis,  Mo. ,  nickel  ores,  440. 
St.  Mary's  mine,  Penn. ,  179. 
Stannite,  445. 

Star  district,  Utah,  iron  mines,  180. 
Staten  Island  bog  ore,  91. 
Steamboat  Springs,  Nov.,  30,  35,  44, 
57. 

Mercury  mines,  427. 
Stehekin  copper  district,  Wash.,  222. 


Stein  Mt.,  Ore.,  347. 

Stelzner,  A.  W.,  cited,  34. 

Step- faults  defined,  24. 

Sterling  Hill  zinc  mine,  N.  J,,  251- 

257. 
Sterling  mines,  Cayuga  Co.,  N.  Y., 

115. 
Stevens  Co.,  Wash.,  gold,  347. 
Stevenson,  J.  J.,  cited,  50. 
Stibnite,  410. 

Stickeen  river,  Alaska,  394. 
Stobie  nickel  mine,  Ont. ,  436. 
Stokes  Co.,  N.  C,  iron  ore,  170. 
Storey  Co. ,  Nev. ,  silver  and  gold,  340. 
Storms,  W.  H.,  on  Alvord  mine,  Cal.^ 

370. 
Stratum  defined,  6. 
Stratigraphy  of  auriferous  strata,  374. 
Stream  tin,  443. 
Strike-faults,  21,  25. 
Sub-carboniferous  series,  5. 
Succession  of  minerals  in  an  igneous 

rock,  33,  34. 
Sudbury,  Ont.,  Can.,  62. 

Cobalt,  438. 

Iron,  184. 

Nickel,  429,  431. 
Sullivan  Co.,   N.  Y.,   lead  deposits, 

228. 
Sulphur  Bank,  Cal. ,  mercury,  44,  427. 
Sulphur  in  iron  ores,  85,  86. 
Sulphur  in  rocks,  37. 
Sumdum  Bay,  Alaska,  gold  deposits, 

392 
Summit  Co.,  Colo.,  294. 

Lead-silver,  266. 
Summit  Co.,  Utah,  lead-silver,  275. 
Summit  district,  Colo.,  45,  52. 
Sunrise  copper  mines,  Wyo. ,  222. 
Sweden,  lake  ores,  92. 
Sweden,  magnetites,  175. 
Sweet  Grass  Hills,  Mont.,  323. 
Sweetwater  Co.,  Wyo.,  308. 
Swells  in  a  vein,  49. 
Syncline  defined,  11,  17. 


Taberg,  Sweden,  iron  ore,  60,  175. 
Taku  mines,  Alaska,  392. 
TalahCo..  Idaho,  324. 
Tamarack  copper  mine,  Mich. ,  208. 
Tarr,  R.  S.,  on  Cape  Ann  granite,  13, 

14. 
On  classification  of  ore  deposits, 

459. 
Telegraph  lead-silver  mine,  Utah,  275. 
Teller  Co.,  Colo.,  300. 
Telluride,  Colo.,  288. 
Tellurides  in  gold  quartz,  362. 
Temescal  tin  mine,  Cal. ,  443. 


INDEX. 


479 


Tern  Pahute  district,  Nev.,  338. 
Ten-mile  district,  Colo.*,  266,  294. 
Tennessee,  Clinton  ore,  114,  116. 
Copper,  194. 
Lead  zinc,  249. 

Limonite,  96,  103. 
Manganese,  420. 
Tennessee  mine,  Polk  Co.,  Tenn.,  192. 
Tenny  Cape,  Nova  Scotia,  422. 
Terrace  series,  5. 
Terrane  defined,  6. 
Terry  Peak,  S.  D.,  311. 
Tertiary  system,  5. 
Teton  Co.,  Mont.,  321. 
Texas,  copper  ores,  204,  224. 

Limonite,  97,  98. 

Mercury,  424,  428. 

Tin,  444. 
Texas  mine,  chromite,  415. 
Texas,  Penn.,  nickel  ore,  439. 
Thies-Hutchins    antimony    mines, 

Nev.,  411. 
Three  Rivers,  Que.,  bog  ore,  90. 
Thunder  Bay,  Can.,  284. 
Tilly  Foster  iron  mine,  N.  Y.,  166.. 
Tilt  Cove,  N.  F.,  nickel  ore,  429. 
Tin,  concluding  remarks,  445. 

Deposits,  69,  70. 

Veins.  72. 
Tin  Cup,  Colo.,  294. 
Tintic  district,  Utah,  copper  mines, 
221. 

Lead-silver  mines,  275. 
Tioga  Co.,  Penn.,  121. 
Titaniferous  magnetite,  160,  165. 

In  the  Adirondacks,  171. 

In  Canada,  172. 

Colorado,  174. 

Minnesota,  174. 

New  Jersey,  173. 

North  Carolina,  174. 
*       Norway,  173. 

Sweden,  172. 

Virginia,  171. 

Wyoming,  171. 
Titanium  in  iron  ores,  85,  86. 
Titcomb,  H.  A.,  cited,  352. 
Tombstone,  Ariz.,  43,  336. 
Torrington,  Conn.,  nickel  ores,  430. 
Tower,  G.  W. ,  on  Butte  copper  ores, 

197. 
Tower,  Mich.,  85. 
Toyabe  Range,  Nev.,  339. 
Trail  Creek  district,  B.  C,  394. 
Trail  of  a  fault,  23. 
Treadwell  mine,  Alaska,  390. 
Trenton  series  and  stage,  4. 
Triassic  system,  5. 
Trigg  Co.,  Ky.,  95. 
Trotter  zinc  mine,  N.  J.,  252. 


Tucson,  Ariz.,  336. 

Tuolumne  Co.,  Cal.,  363. 

Turner,     H.    W.,    California      gold 

gravels,  359. 
Tuscaloosa  stage,  5. 
Tuscarora  district,  Nev. ,  340. 
Tybo,  Nev.,  338. 

Tyrrell,  on  Alaska  gold  gravels,  393. 
Tyson,  I.,  Jr.,  on  chromite  market. 

414. 


U 

Ueberroth  zinc  mine,  Penn.,  250. 

Uintah  Mt.,  Utah,  325. 

Uinta  stage,  5. 

Ulster  Co.,  N.  Y.,  lead  deposits,  229. 

Limonites,  111. 
United  States  Antimony  Co.,  Phila.. 

411. 
United  States,  geological  review  of 
the,  8-10. 

Topography  of  the,  7,  8. 

Magnetite  sands,  181. 
United  Verde  copper  mine,  Ariz.,  220. 
Utah,  antimony,  411. 

Copper,  224. 

Geology,  ,328. 

Gold  and  silver,  329. 

Limonite,  100. 

Mercury,  424. 

Silver-bearing  sandstone,  68. 
Utica  stage,  4. 


Vadose  circulation,  27. 

Vanadium  distribution,  36. 

Van  Diest,  P.  H.,  on  Boulder  Co., 

Colo.,  306. 
Van  Dyck,  F.  C,  analysis  by,  254. 
Van  Hise,  C.  R.,  cited,  44. 

On    classification    of    Michigan 
ores,  133. 

On  joints,  14. 

On  Marquette  district,  129. 

On  Penokee  district,  139. 

On  zones  of  fracture,  25. 
Van  Wagenen,  T.  F.,  cited,  53. 
Veins,  changes  in  filling,  50. 

Methods  of  filling,  39. 

Swells,  49. 
Vermilion  district,  Minn.,  134. 

Lake,  iron  mines,  144-146. 
Vermont  chromite,  416. 

Gold,  383. 

Iron,  184. 

Lead,  227. 

Limonite,  100. 

Manganese,  418. 
Vershire,  Vt.,  copper  ore,  184,  190 


480 


INDEX. 


Verticals  in  gold  mines,  Black  Hills, 

312. 
Vicksburg  stage,  5. 
Victor  mines,  Colo. ,  385. 
Virginia,  Clinton  ore,  114,  116. 

Gold  deposits,  381. 

Lead  and  zinc,  347. 

Liraonite  or  brown  hematite,  87- 
114. 

Magnetite,  169. 

Manganese,  418. 
Virginia  City,  Mont.,  316. 
Vivianite  in  bog  ore,  89. 
Vogelsberg,     Germany,     aluminum, 

407. 
Vogt.  J.  H.  L. ,  on  chromite,  413. 

On  ore  deposits,  61-65. 

On  nickel  ores,  434. 

On  sulphides  of  iron,  185. 
Vuggs  of  a  vein,  48. 

W 

Wabner,  R.,  cited,  55. 
Wadsworth,  M.  E.,  on  iron  ores,  127, 
135. 

On  classification  of  ores,  458 

On  copper  ores,  Keweenaw,  205. 

On  Marquette  district,  128. 

On  origin  of  copper  ores,  211. 
Wahnapitae  Lake  nickel  mines.  Can., 

436. 
Walcott,  C.  D.,  on  fossils  of  Montana, 

315. 
Walker,  T.  L. ,  on  nickel  ore,  437. 
Wallingford,  Vt. ,  manganese  ore,  418. 
Wardner.  Idaho,  lead -silver    mines, 

274. 
War  Eagle  mine,  B.  C,  397. 
Wasatch  Mt.,  Mont.,  314. 

Utah,  180,  274. 
Wasatch  stage,  5. 
Washington  Co.,  Mo.,  lead  and  zinc 

mines,  239. 
Washington  copper  deposits,  322. 

Geology,  346. 

Silver,  347. 
Washoe  Co.,  Nev.,  gold  and  silver 

mines,  340. 
Water,  underground,  26-33. 
Waukon,  Iowa,  limonite,  98. 
Wawa  Lake  gold  deposits,  385. 
Wayne  Co.,  N.  Y.,  Clinton  ore,  115. 
Waynesburg  coal  seam,  107. 
Webster,  N.  C,  nickel,  439. 
Weed,  W.  H.,  on  copper  deposits,  197. 

On  gold  deposits,  Montana,  315. 

On  sinters,  68. 

On  vein  formation,  38. 
Weissenbach,  von,  cited,  47, 


Weissenbach,    von,    on    scheme    of 

classification  of  ore,  448. 
Wells,  Professor,  cited,  441. 
Wendt,  A.,  mineral  veins,  51. 
Werner,  cited  on  his  epoch,  55. 
Westport,  N.  Y.,  magnetite,  172. 
Weston  mine,  N.  Y.,  162. 
West  Stockbridge,    Mass.,    limonite, 

101. 
West  Virginia,  Clinton  ore,  114. 

Limonite,  107. 

Red  hematite,  121. 
Wet  Mt.  Valley,  Colo.,  296. 
Wheatfield  mine,  Penn.,  179. 
Wheatley  lead  mine,  Penn.,  227, 
White  Oak  gold  district,  N.  M.,  385. 
White  Pine  Co.,  Nev.,  338. 
White  River  stage,  5. 
White  Quail  mine,  Colo.,  267. 
Whitney,  J.  D.,  on  California  grav- 
els, 356. 

On  origin  Michigan  iron  ore,  135. 

On  Missouri  ores,  158. 

On  lead  ores,  236-42. 

On  Mother  lode,  CaUfornia,  364. 

On  scheme  of    classification  of 
ores,  453. 

On  Seaweed,  68. 
Wickes,  Mont. ,  lead-silver  mines,  373. 
Williams.  G.  H.,  cited,  138. 

On  chromite,  415. 

On  manganese,  430. 
WilKs,  B.,  cited,  178. 
Willow  Creek,  Idaho,  325. 
Wiltsee,  E. ,  on  Half  Moon  mine,  Nev. 

338. 
Winchell,  H.  V.,  on  Rainy  Lake  dis- 
trict, 384. 
Winchell,  N.  H.,  and  H.  V,  on  Pen- 

okee  iron  ore,  150. 
Wind  River  stage.  5. 
Winslow,  A.,  Missouri  lead  and  zino 
mines,  230-244. 

On  Tin,  444. 
Winston,  Mont.,  319. 
Wisconsin,  Clinton  ore,  114. 

Lead  and  zinc  mines,  68,  233. 
Wisconsin  Island,  9. 
Wolff,  J.  E.,  on  Hibernia  magnetite, 
168. 

On  New  Jersey  zinc  deposits,  252. 
Woodman,  J.    E.,  Nova  Scotia  gold, 

399. 
Wood  River  mines,  Idaho,  lead-silver, 

273,  327. 
Woods  mine,  chromite,  414. 
Woodworth,  J.  B.,  on  joints,  15. 
Worthington  nickel  mine,  436. 
Wyoming,  copper  mines,  223. 

Geology  of,  308. 


INDEX. 


481 


Wyoming  iron  mines,  171. 

Tin  ores,  443. 
Wythe  Co.,  Va.,  zinc,  247,  248. 


Yak  River,  Mont.,  323. 

Yakima  Co.,   Wash.,   placer  mines, 

347. 
/akutat  Bay,    Alaska,    gold    sands, 

349. 
Yavapai  Co.,  Ariz.,  gold,  silver  ores, 

335. 
Yellow  Jacket  mines,  Idaho,  324. 


Yogo  Gulch,  Mont.,  aluminmn,  410. 
York  Co.,  N.  B.,  antimony,  411. 
York  Co.,  Penn.,  iron  ores,  101,  179. 
Yukon  Basin,  Alaska,  393. 
Yukon  silts,  389. 
Yuma  Co.,  Ariz.,  335-337, 

Z 
Zinc  minerals,  250. 

Analyses,  254. 

Statistics,  259. 
Zone  of  fracture  in  the  earth,  25. 

Of  oxidized  ores,  50-52. 


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